{"entity":{"type":"insider","cik":"0001450414","url":"/insider/0001450414","json_url":"/insider/0001450414.json","name":"WESTERN STANDARD PARTNERS LP","name_source":"as-filed","also_issuer":false,"cross_url":null},"coverage_statement":{"n_transactions":64,"n_filings":27,"first":"2011-04-08","last":"2023-12-28","span_basis":"filed_date"},"name_variants":[{"name":"WESTERN STANDARD PARTNERS LP","source":"filing","n_filings":27,"first_seen":"2011-04-08","last_seen":"2023-12-28"}],"transactions":[{"id":8108930,"accession":"0000950170-23-073585","txn_seq":2,"anchor":"line-2","filing_url":"/filing/0000950170-23-073585","line_url":"/filing/0000950170-23-073585#line-2","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard LLC; Western Standard Partners QP, L.P.","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":857.0,"shares_display":"857","price_per_share":13.3503,"price_display":"13.35","price_state":"stated","total_value":11441.2071,"total_display":"11,441.21","total_whole":"11,441","shares_owned_after":534008.0,"shares_owned_after_display":"534,008","ownership_form":"I","is_10b5_1":null,"transaction_date":"2023-12-28","filed_date":"2023-12-28","scope":"insider"},{"id":8108926,"accession":"0000950170-23-073585","txn_seq":1,"anchor":"line-1","filing_url":"/filing/0000950170-23-073585","line_url":"/filing/0000950170-23-073585#line-1","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard LLC; Western Standard Partners QP, L.P.","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":48693.0,"shares_display":"48,693","price_per_share":13.15,"price_display":"13.15","price_state":"stated","total_value":640312.95,"total_display":"640,312.95","total_whole":"640,313","shares_owned_after":533151.0,"shares_owned_after_display":"533,151","ownership_form":"I","is_10b5_1":null,"transaction_date":"2023-12-26","filed_date":"2023-12-28","scope":"insider"},{"id":8216961,"accession":"0000950170-23-069397","txn_seq":2,"anchor":"line-2","filing_url":"/filing/0000950170-23-069397","line_url":"/filing/0000950170-23-069397","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard LLC; Western Standard Partners QP, L.P.","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":101050.0,"shares_display":"101,050","price_per_share":12.8498,"price_display":"12.85","price_state":"stated","total_value":1298472.29,"total_display":"1,298,472.29","total_whole":"1,298,472","shares_owned_after":1735600.0,"shares_owned_after_display":"1,735,600","ownership_form":"I","is_10b5_1":null,"transaction_date":"2023-12-07","filed_date":"2023-12-11","scope":"insider","n_lines":2},{"id":8599756,"accession":"0000950170-23-065235","txn_seq":2,"anchor":"line-2","filing_url":"/filing/0000950170-23-065235","line_url":"/filing/0000950170-23-065235","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard LLC; Western Standard Partners QP, L.P.","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":300.0,"shares_display":"300","price_per_share":12.5,"price_display":"12.50","price_state":"stated","total_value":3750.0,"total_display":"3,750.00","total_whole":"3,750","shares_owned_after":1659216.0,"shares_owned_after_display":"1,659,216","ownership_form":"I","is_10b5_1":null,"transaction_date":"2023-11-17","filed_date":"2023-11-20","scope":"insider","n_lines":2},{"id":8599708,"accession":"0000950170-23-064564","txn_seq":2,"anchor":"line-2","filing_url":"/filing/0000950170-23-064564","line_url":"/filing/0000950170-23-064564","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard LLC; Western Standard Partners QP, L.P.","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":50170.0,"shares_display":"50,170","price_per_share":12.5,"price_display":"12.50","price_state":"stated","total_value":627125.0,"total_display":"627,125.00","total_whole":"627,125","shares_owned_after":1658981.0,"shares_owned_after_display":"1,658,981","ownership_form":"I","is_10b5_1":null,"transaction_date":"2023-11-14","filed_date":"2023-11-16","scope":"insider","n_lines":2},{"id":7940354,"accession":"0000950170-23-063800","txn_seq":4,"anchor":"line-4","filing_url":"/filing/0000950170-23-063800","line_url":"/filing/0000950170-23-063800","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard LLC; Western Standard Partners QP, L.P.","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":15570.0,"shares_display":"15,570","price_per_share":12.3876,"price_display":"12.39","price_state":"stated","total_value":192874.932,"total_display":"192,874.93","total_whole":"192,875","shares_owned_after":1619698.0,"shares_owned_after_display":"1,619,698","ownership_form":"I","is_10b5_1":null,"transaction_date":"2023-11-13","filed_date":"2023-11-14","scope":"insider","n_lines":2},{"id":7940351,"accession":"0000950170-23-063800","txn_seq":2,"anchor":"line-2","filing_url":"/filing/0000950170-23-063800","line_url":"/filing/0000950170-23-063800","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard LLC; Western Standard Partners QP, L.P.","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":38062.0,"shares_display":"38,062","price_per_share":12.3222,"price_display":"12.32","price_state":"stated","total_value":469007.5764,"total_display":"469,007.58","total_whole":"469,008","shares_owned_after":1607507.0,"shares_owned_after_display":"1,607,507","ownership_form":"I","is_10b5_1":null,"transaction_date":"2023-11-10","filed_date":"2023-11-14","scope":"insider","n_lines":2},{"id":8012031,"accession":"0000950170-23-062911","txn_seq":4,"anchor":"line-4","filing_url":"/filing/0000950170-23-062911","line_url":"/filing/0000950170-23-062911","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard LLC; Western Standard Partners QP, L.P.","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":9975.0,"shares_display":"9,975","price_per_share":12.1923,"price_display":"12.19","price_state":"stated","total_value":121618.1925,"total_display":"121,618.19","total_whole":"121,618","shares_owned_after":1577704.0,"shares_owned_after_display":"1,577,704","ownership_form":"I","is_10b5_1":null,"transaction_date":"2023-11-09","filed_date":"2023-11-13","scope":"insider","n_lines":2},{"id":8012026,"accession":"0000950170-23-062911","txn_seq":2,"anchor":"line-2","filing_url":"/filing/0000950170-23-062911","line_url":"/filing/0000950170-23-062911","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard LLC; Western Standard Partners QP, L.P.","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":13823.0,"shares_display":"13,823","price_per_share":12.132,"price_display":"12.13","price_state":"stated","total_value":167700.636,"total_display":"167,700.64","total_whole":"167,701","shares_owned_after":435037.0,"shares_owned_after_display":"435,037","ownership_form":"I","is_10b5_1":null,"transaction_date":"2023-11-08","filed_date":"2023-11-13","scope":"insider","n_lines":2},{"id":8216666,"accession":"0000950170-23-040559","txn_seq":4,"anchor":"line-4","filing_url":"/filing/0000950170-23-040559","line_url":"/filing/0000950170-23-040559","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard LLC; Western Standard Partners QP, L.P.","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":87057.0,"shares_display":"87,057","price_per_share":11.9959,"price_display":"12.00","price_state":"stated","total_value":1044327.0663,"total_display":"1,044,327.07","total_whole":"1,044,327","shares_owned_after":1565111.0,"shares_owned_after_display":"1,565,111","ownership_form":"I","is_10b5_1":null,"transaction_date":"2023-08-08","filed_date":"2023-08-09","scope":"insider","n_lines":2},{"id":8216659,"accession":"0000950170-23-040559","txn_seq":2,"anchor":"line-2","filing_url":"/filing/0000950170-23-040559","line_url":"/filing/0000950170-23-040559","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard LLC; Western Standard Partners QP, L.P.","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":134493.0,"shares_display":"134,493","price_per_share":12.0037,"price_display":"12.00","price_state":"stated","total_value":1614413.6241,"total_display":"1,614,413.62","total_whole":"1,614,414","shares_owned_after":1496680.0,"shares_owned_after_display":"1,496,680","ownership_form":"I","is_10b5_1":null,"transaction_date":"2023-08-07","filed_date":"2023-08-09","scope":"insider","n_lines":2},{"id":8425767,"accession":"0000950170-23-009171","txn_seq":2,"anchor":"line-2","filing_url":"/filing/0000950170-23-009171","line_url":"/filing/0000950170-23-009171","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard LLC; Western Standard Partners QP, L.P.","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":160590.0,"shares_display":"160,590","price_per_share":11.52,"price_display":"11.52","price_state":"stated","total_value":1849996.8,"total_display":"1,849,996.80","total_whole":"1,849,997","shares_owned_after":1412044.0,"shares_owned_after_display":"1,412,044","ownership_form":"I","is_10b5_1":null,"transaction_date":"2023-03-21","filed_date":"2023-03-22","scope":"insider","n_lines":2},{"id":9205337,"accession":"0000899243-23-006607","txn_seq":3,"anchor":"line-3","filing_url":"/filing/0000899243-23-006607","line_url":"/filing/0000899243-23-006607","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard LLC; Western Standard Partners QP, L.P.","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":2232.0,"shares_display":"2,232","price_per_share":11.3998,"price_display":"11.40","price_state":"stated","total_value":25444.3536,"total_display":"25,444.35","total_whole":"25,444","shares_owned_after":1284635.0,"shares_owned_after_display":"1,284,635","ownership_form":"I","is_10b5_1":null,"transaction_date":"2023-01-31","filed_date":"2023-03-01","scope":"insider","n_lines":2},{"id":7833958,"accession":"0000899243-23-003115","txn_seq":4,"anchor":"line-4","filing_url":"/filing/0000899243-23-003115","line_url":"/filing/0000899243-23-003115","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"WESTERN STANDARD PARTNERS LP; Andersen Eric; Western Standard LLC; Western Standard Partners QP, L.P.","owner_display_name":"WESTERN STANDARD PARTNERS LP","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":2232.0,"shares_display":"2,232","price_per_share":11.3998,"price_display":"11.40","price_state":"stated","total_value":25444.3536,"total_display":"25,444.35","total_whole":"25,444","shares_owned_after":1284635.0,"shares_owned_after_display":"1,284,635","ownership_form":"I","is_10b5_1":null,"transaction_date":"2023-01-31","filed_date":"2023-02-01","scope":"insider","n_lines":2},{"id":9205338,"accession":"0000899243-23-006607","txn_seq":2,"anchor":"line-2","filing_url":"/filing/0000899243-23-006607","line_url":"/filing/0000899243-23-006607","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard LLC; Western Standard Partners QP, L.P.","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":24735.0,"shares_display":"24,735","price_per_share":11.3576,"price_display":"11.36","price_state":"stated","total_value":280930.236,"total_display":"280,930.24","total_whole":"280,930","shares_owned_after":323883.0,"shares_owned_after_display":"323,883","ownership_form":"I","is_10b5_1":null,"transaction_date":"2023-01-30","filed_date":"2023-03-01","scope":"insider","n_lines":2},{"id":7833952,"accession":"0000899243-23-003115","txn_seq":2,"anchor":"line-2","filing_url":"/filing/0000899243-23-003115","line_url":"/filing/0000899243-23-003115","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"WESTERN STANDARD PARTNERS LP; Andersen Eric; Western Standard LLC; Western Standard Partners QP, L.P.","owner_display_name":"WESTERN STANDARD PARTNERS LP","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":24708.0,"shares_display":"24,708","price_per_share":11.3576,"price_display":"11.36","price_state":"stated","total_value":280623.5808,"total_display":"280,623.58","total_whole":"280,624","shares_owned_after":1282853.0,"shares_owned_after_display":"1,282,853","ownership_form":"I","is_10b5_1":null,"transaction_date":"2023-01-30","filed_date":"2023-02-01","scope":"insider","n_lines":2},{"id":8213299,"accession":"0000899243-23-003033","txn_seq":2,"anchor":"line-2","filing_url":"/filing/0000899243-23-003033","line_url":"/filing/0000899243-23-003033","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"WESTERN STANDARD PARTNERS LP; Western Standard Partners QP, L.P.; Andersen Eric; Western Standard LLC","owner_display_name":"WESTERN STANDARD PARTNERS LP","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":21875.0,"shares_display":"21,875","price_per_share":11.3965,"price_display":"11.40","price_state":"stated","total_value":249298.4375,"total_display":"249,298.44","total_whole":"249,298","shares_owned_after":1263103.0,"shares_owned_after_display":"1,263,103","ownership_form":"I","is_10b5_1":null,"transaction_date":"2023-01-27","filed_date":"2023-01-31","scope":"insider","n_lines":2},{"id":8527629,"accession":"0000899243-23-000581","txn_seq":2,"anchor":"line-2","filing_url":"/filing/0000899243-23-000581","line_url":"/filing/0000899243-23-000581","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; Western Standard LLC; WESTERN STANDARD PARTNERS LP; Western Standard Partners QP, L.P.","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":30632.0,"shares_display":"30,632","price_per_share":11.3332,"price_display":"11.33","price_state":"stated","total_value":347158.5824,"total_display":"347,158.58","total_whole":"347,159","shares_owned_after":1245638.0,"shares_owned_after_display":"1,245,638","ownership_form":"I","is_10b5_1":null,"transaction_date":"2023-01-03","filed_date":"2023-01-04","scope":"insider","n_lines":2},{"id":8740546,"accession":"0000899243-23-000225","txn_seq":4,"anchor":"line-4","filing_url":"/filing/0000899243-23-000225","line_url":"/filing/0000899243-23-000225","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Western Standard LLC; Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard Partners QP, L.P.","owner_display_name":"Western Standard LLC","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":41300.0,"shares_display":"41,300","price_per_share":11.3327,"price_display":"11.33","price_state":"stated","total_value":468040.51,"total_display":"468,040.51","total_whole":"468,041","shares_owned_after":1223225.0,"shares_owned_after_display":"1,223,225","ownership_form":"I","is_10b5_1":null,"transaction_date":"2022-12-30","filed_date":"2023-01-03","scope":"insider","n_lines":2},{"id":8740542,"accession":"0000899243-23-000225","txn_seq":2,"anchor":"line-2","filing_url":"/filing/0000899243-23-000225","line_url":"/filing/0000899243-23-000225","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Western Standard LLC; Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard Partners QP, L.P.","owner_display_name":"Western Standard LLC","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":218636.0,"shares_display":"218,636","price_per_share":10.5503,"price_display":"10.55","price_state":"stated","total_value":2306675.3908,"total_display":"2,306,675.39","total_whole":"2,306,675","shares_owned_after":1190195.0,"shares_owned_after_display":"1,190,195","ownership_form":"I","is_10b5_1":null,"transaction_date":"2022-12-29","filed_date":"2023-01-03","scope":"insider","n_lines":2},{"id":9205041,"accession":"0000899243-21-036576","txn_seq":4,"anchor":"line-4","filing_url":"/filing/0000899243-21-036576","line_url":"/filing/0000899243-21-036576#line-4","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard LLC; Western Standard Partners QP, L.P.","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"S","transaction_label":"Open-market sale","open_market":true,"acquired_disposed":"D","direction_word":"disposed","shares":52914.0,"shares_display":"52,914","price_per_share":6.39,"price_display":"6.39","price_state":"stated","total_value":338120.46,"total_display":"338,120.46","total_whole":"338,120","shares_owned_after":269338.0,"shares_owned_after_display":"269,338","ownership_form":"I","is_10b5_1":null,"transaction_date":"2021-07-01","filed_date":"2021-09-20","scope":"insider"},{"id":9205040,"accession":"0000899243-21-036576","txn_seq":3,"anchor":"line-3","filing_url":"/filing/0000899243-21-036576","line_url":"/filing/0000899243-21-036576#line-3","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard LLC; Western Standard Partners QP, L.P.","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":52914.0,"shares_display":"52,914","price_per_share":6.39,"price_display":"6.39","price_state":"stated","total_value":338120.46,"total_display":"338,120.46","total_whole":"338,120","shares_owned_after":1000220.0,"shares_owned_after_display":"1,000,220","ownership_form":"I","is_10b5_1":null,"transaction_date":"2021-07-01","filed_date":"2021-09-20","scope":"insider"},{"id":9205043,"accession":"0000899243-21-036576","txn_seq":2,"anchor":"line-2","filing_url":"/filing/0000899243-21-036576","line_url":"/filing/0000899243-21-036576","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard LLC; Western Standard Partners QP, L.P.","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":47300.0,"shares_display":"47,300","price_per_share":6.6329,"price_display":"6.63","price_state":"stated","total_value":313736.17,"total_display":"313,736.17","total_whole":"313,736","shares_owned_after":322252.0,"shares_owned_after_display":"322,252","ownership_form":"I","is_10b5_1":null,"transaction_date":"2021-04-14","filed_date":"2021-09-20","scope":"insider","n_lines":2},{"id":5318525,"accession":"0000899243-21-016103","txn_seq":2,"anchor":"line-2","filing_url":"/filing/0000899243-21-016103","line_url":"/filing/0000899243-21-016103","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard Partners QP, L.P.; Western Standard LLC","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":47300.0,"shares_display":"47,300","price_per_share":6.6329,"price_display":"6.63","price_state":"stated","total_value":313736.17,"total_display":"313,736.17","total_whole":"313,736","shares_owned_after":947396.0,"shares_owned_after_display":"947,396","ownership_form":"I","is_10b5_1":null,"transaction_date":"2021-04-14","filed_date":"2021-04-16","scope":"insider","n_lines":2},{"id":4812072,"accession":"0000899243-21-015953","txn_seq":1,"anchor":"line-1","filing_url":"/filing/0000899243-21-015953","line_url":"/filing/0000899243-21-015953#line-1","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard Partners QP, L.P.; Western Standard LLC","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":9874.0,"shares_display":"9,874","price_per_share":6.2568,"price_display":"6.26","price_state":"stated","total_value":61779.6432,"total_display":"61,779.64","total_whole":"61,780","shares_owned_after":906591.0,"shares_owned_after_display":"906,591","ownership_form":"I","is_10b5_1":null,"transaction_date":"2021-04-13","filed_date":"2021-04-15","scope":"insider"},{"id":4450680,"accession":"0000899243-21-015803","txn_seq":1,"anchor":"line-1","filing_url":"/filing/0000899243-21-015803","line_url":"/filing/0000899243-21-015803#line-1","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; Western Standard LLC; WESTERN STANDARD PARTNERS LP; Western Standard Partners QP, L.P.","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":23629.0,"shares_display":"23,629","price_per_share":6.0601,"price_display":"6.06","price_state":"stated","total_value":143194.1029,"total_display":"143,194.10","total_whole":"143,194","shares_owned_after":896717.0,"shares_owned_after_display":"896,717","ownership_form":"I","is_10b5_1":null,"transaction_date":"2021-04-12","filed_date":"2021-04-14","scope":"insider"},{"id":2385496,"accession":"0000899243-20-032257","txn_seq":2,"anchor":"line-2","filing_url":"/filing/0000899243-20-032257","line_url":"/filing/0000899243-20-032257","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Andersen Eric; WESTERN STANDARD PARTNERS LP; Western Standard Partners QP, L.P.; Western Standard LLC","owner_display_name":"Andersen Eric","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":69088.0,"shares_display":"69,088","price_per_share":3.65,"price_display":"3.65","price_state":"stated","total_value":252171.2,"total_display":"252,171.20","total_whole":"252,171","shares_owned_after":873088.0,"shares_owned_after_display":"873,088","ownership_form":"I","is_10b5_1":null,"transaction_date":"2020-11-24","filed_date":"2020-11-27","scope":"insider","n_lines":2},{"id":3203789,"accession":"0000899243-20-031116","txn_seq":2,"anchor":"line-2","filing_url":"/filing/0000899243-20-031116","line_url":"/filing/0000899243-20-031116","is_derivative":false,"issuer_cik":"0001274792","issuer_name":"MERRIMACK PHARMACEUTICALS INC","issuer_ticker":"MACK","issuer_name_source":null,"issuer_url":"/issuer/0001274792","owner_cik":null,"owner_name":"Western Standard Partners QP, L.P.; Western Standard LLC; Andersen Eric; WESTERN STANDARD PARTNERS LP","owner_display_name":"Western Standard Partners QP, L.P.","owner_url":null,"role":"Director, Other","role_mark":null,"role_mark_label":"Not attributed","role_mark_generic":"Not stated","n_reporting_owners":4,"other_reporting_owners":3,"officer_title":null,"security_title":"Common Stock","transaction_code":"P","transaction_label":"Open-market purchase","open_market":true,"acquired_disposed":"A","direction_word":"acquired","shares":56490.0,"shares_display":"56,490","price_per_share":3.65,"price_display":"3.65","price_state":"stated","total_value":206188.5,"total_display":"206,188.50","total_whole":"206,189","shares_owned_after":297743.0,"shares_owned_after_display":"297,743","ownership_form":"I","is_10b5_1":null,"transaction_date":"2020-11-12","filed_date":"2020-11-16","scope":"insider","n_lines":2}],"collapsed":true,"next_cursor":"2020-11-12|3203785","ledger_fault":false,"count":{"value":0,"kind":"exact"},"open_market_only":false,"composition":{"kind":"exact","rows":[{"code":"P","label":"Open-market purchase","n":0,"open_market":true},{"code":"S","label":"Open-market sale","n":0,"open_market":true},{"code":"M","label":"Option exercise","n":0,"open_market":false},{"code":"A","label":"Grant or award","n":0,"open_market":false},{"code":"F","label":"Tax withholding","n":0,"open_market":false},{"code":"D","label":"Disposition to the issuer","n":0,"open_market":false},{"code":"X","label":"In-the-money option exercise","n":0,"open_market":false}],"total":0},"affiliations":[{"type":"issuer","type_label":"ISSUER","cik":"0001274792","name":"MERRIMACK PHARMACEUTICALS INC","url":"/issuer/0001274792","role":"Other","n_filings":25,"first_seen":"2020-04-07","last_seen":"2023-12-28"},{"type":"issuer","type_label":"ISSUER","cik":"0000314727","name":"HANDLEMAN CO /MI/","url":"/issuer/0000314727","role":"Ten percent owner","n_filings":2,"first_seen":"2011-04-08","last_seen":"2011-04-08"}],"order_statement":"Newest transaction date first, id breaking the tie.","canonical_url":"https://ebomi.com/insider/0001450414","retrieved_at":"2026-08-22T17:00:00+00:00","coverage":{"filings":1506293,"transactions":4290787,"issuers":28597,"insiders":152303,"first_filed_date":"2003-06-30","last_filed_date":"2026-08-21","last_ingest":"2026-08-22T05:23:40.159918+00:00","counts_are":{"filings":"estimate","transactions":"estimate","issuers":"estimate","insiders":"estimate"},"source":"SEC EDGAR Form 4 filings, parsed by ebomi","fault":false},"license":{"underlying_records":"US SEC filings are public records of the United States government and are not subject to copyright. The transactional facts in them are not ours to license.","this_presentation":"The parsing, normalisation, curation, and presentation are ebomi's own work.","grant":"undecided","grant_note":"The open licence for ebomi's own layer is an open owner decision (SPEC-20260731T1159Z open question 3: CC BY 4.0 or CC0 with a citation request). Until it is taken, no grant is asserted here.","citation_request":"Balogh, A. Insider trading. Scientific Data 10, 237 (2023)","url":"https://ebomi.com/license"},"fair_use":{"policy":"These JSON endpoints are open and unauthenticated. Please read them at a human pace, identify your client in the User-Agent header, and use the published dataset for bulk work rather than crawling page by page.","bulk_alternative":"doi:10.1038/s41597-023-02147-6"}}