| Innospec Ltd | Innospec | chemicals | bribery | 2010 | UK-SFO | £8,528,940 |
| Intergen | | | energy market violation | 2015 | UK-OFGEM | £11,000,000 |
| InterGen | | | energy market violation | 2020 | UK-OFGEM | £37,200,000 |
| International Tubular Services Limited | | | bribery | 2014 | UK-COPFS | £172,200 |
| ION Investment Group Limited and ION Trading Technologies Limited | | | price-fixing or anti-competitive practices | 2021 | UK-CMA | £325,000 |
| iSupply | | | consumer protection violation | 2020 | UK-OFGEM | £1,500,000 |
| iSupply Energy | | | consumer protection violation | 2020 | UK-OFGEM | £520,539 |
| iSupply Energy | | | consumer protection violation | 2019 | UK-OFGEM | £28,183 |
| ITW Limited | Illinois Tool Works | industrial equipment | price-fixing or anti-competitive practices | 2016 | UK-CMA | £2,298,820 |
| J Sainsbury plc | J Sainsbury PLC | retailing | price-fixing or anti-competitive practices | 2023 | UK-CMA | £0 |
| JCDecaux UK | | | price-fixing or anti-competitive practices | 2012 | UK-OFT | £0 |
| JD Sports | JD Sports Fashion | retailing | price-fixing or anti-competitive practices | 2022 | UK-CMA | £4,320,000 |
| JD Sports Fashion Plc | JD Sports Fashion | retailing | price-fixing or anti-competitive practices | 2022 | UK-CMA | £1,485,000 |
| JD Sports Fashion plc | JD Sports Fashion | retailing | price-fixing or anti-competitive practices | 2023 | UK-CMA | £0 |
| John F Hunt Ltd and John F Hunt Group Ltd | | | price-fixing or anti-competitive practices | 2023 | UK-CMA | £5,600,000 |
| John Wood Group PLC | Wood Group | oilfield services and supplies | bribery | 2017 | UK-COPFS | £6,460,000 |
| JPMorgan Chase Bank N.A. | JPMorgan Chase | financial services | foreign exchange market manipulation | 2014 | UK-FCA | £222,166,000 |
| Keltbray Ltd and Keltbray Holdings Ltd | | | price-fixing or anti-competitive practices | 2023 | UK-CMA | £16,000,000 |
| King Pharmaceuticals Ltd. and Praze Consultants Ltd. | | | price-fixing or anti-competitive practices | 2020 | UK-CMA | £75,573 |
| King Pharmaceuticals Ltd. and Praze Consultants Ltd. | | | price-fixing or anti-competitive practices | 2020 | UK-CMA | £75,573 |
| Korg (UK) Ltd. and Korg Inc. | | | price-fixing or anti-competitive practices | 2020 | UK-CMA | £1,504,707 |
| KW Supplies Ltd. | | | price-fixing or anti-competitive practices | 2016 | UK-CMA | £22,248 |
| Lactalis McLelland Limited | Lactalis | food products | price-fixing or anti-competitive practices | 2011 | UK-OFT | £1,660,000 |
| LCC Trans-Sending Ltd. and Small World Financial Services Group Ltd. t/a Small World | | | price-fixing or anti-competitive practices | 2023 | UK-FCA | £139,500 |
| Leicester City Football Club Limited | | | price-fixing or anti-competitive practices | 2023 | UK-CMA | £880,000 |
| Lexon (UK) Limited | Bestway Healthcare | healthcare services | price-fixing or anti-competitive practices | 2021 | UK-CMA | £1,220,383 |
| Lexon (UK) Limited | Bestway Healthcare | healthcare services | price-fixing or anti-competitive practices | 2022 | UK-CMA | £6,706,220 |
| Lexon (UK) Limited and Lexon UK Holdings Limited | Bestway Healthcare | healthcare services | price-fixing or anti-competitive practices | 2022 | UK-CMA | £593,780 |
| Liverpool Victoria Insurance Company Ltd | Allianz | financial services | price-fixing or anti-competitive practices | 2011 | UK-OFT | £0 |
| Lloyds Bank plc and Bank of Scotland plc | Lloyds Banking Group | financial services | interest rate benchmark manipulation | 2014 | UK-FCA | £105,000,000 |
| Loop Interiors London LLP and Loop Interiors Ltd. | | | price-fixing or anti-competitive practices | 2019 | UK-CMA | £1,090,816 |
| M.G.F (Trench Construction Systems) Ltd | | | price-fixing or anti-competitive practices | 2020 | UK-CMA | £3,773,910 |
| M.W. Kellogg Limited | | | bribery | 2011 | UK-SFO | £7,028,077 |
| Mabey Hire Ltd | | | price-fixing or anti-competitive practices | 2020 | UK-CMA | £0 |
| Macmillan Publishers Limited | Holtzbrinck Publishing Group | media | bribery | 2011 | UK-SFO | £11,263,852 |
| Marks and Spencer plc | Marks and Spencer Group PLC | retailing | price-fixing or anti-competitive practices | 2023 | UK-CMA | £0 |
| Martin Brokers (UK) Ltd | | | interest rate benchmark manipulation | 2014 | UK-FCA | £630,000 |
| Mastercard | MasterCard | financial services | price-fixing or anti-competitive practices | 2022 | UK-PSR | £31,560,062 |
| McGee Group (Holdings) Ltd | | | price-fixing or anti-competitive practices | 2023 | UK-CMA | £3,766,278 |
| Medreich plc and Medreich Ltd | Meiji Group | food products | price-fixing or anti-competitive practices | 2022 | UK-CMA | £1,167,554 |
| Medreich plc and Medreich Ltd and Meiji Seika Pharma Co. Ltd and Meiji Holdings Co. Ltd. | Meiji Group | food products | price-fixing or anti-competitive practices | 2022 | UK-CMA | £3,452,446 |
| Mercedes-Benz UK Limited and Daimler UK Limited and Daimler AG | Mercedes-Benz Group | motor vehicles | price-fixing or anti-competitive practices | 2013 | UK-OFT | £1,492,646 |
| Meta Platforms, Inc. and Tabby Acquisition Sub Inc. and Facebook UK Ltd. | Meta Platforms Inc. | information technology | price-fixing or anti-competitive practices | 2022 | UK-CMA | £1,500,000 |
| Michael Hardy & Company (Wokingham) Limited and Geocharbert UK Ltd | | | price-fixing or anti-competitive practices | 2019 | UK-CMA | £142,843 |
| Micronclean Ltd. fka Fenland Laundries Ltd. | | | price-fixing or anti-competitive practices | 2017 | UK-CMA | £510,118 |
| Milton Keynes Mobility Limited | | | price-fixing or anti-competitive practices | 2014 | UK-OFT | £0 |
| Mobility 4 U Limited | | | price-fixing or anti-competitive practices | 2014 | UK-OFT | £0 |
| Mobility Independence Limited | | | price-fixing or anti-competitive practices | 2013 | UK-OFT | £0 |
| Models One Ltd. and One Worldwide Ltd. and Models 1 New Co Ltd. | | | price-fixing or anti-competitive practices | 2016 | UK-CMA | £394,000 |
| Monzo Bank Limited | | | banking violation | 2021 | UK-CMA | £0 |
| Morgan Stanley & Co. International plc | Morgan Stanley | financial services | energy market violation | 2023 | UK-OFGEM | £5,411,149 |
| Moto Holdings Limited | | | price-fixing or anti-competitive practices | 2022 | UK-CMA | £0 |
| Moto Hospitality Limited | | | price-fixing or anti-competitive practices | 2022 | UK-CMA | £0 |
| Motorola Solutions UK Limited | Motorola Solutions | telecommunications | price-fixing or anti-competitive practices | 2022 | UK-OFCOM | £0 |
| Motorola Solutions, Inc. | Motorola Solutions | telecommunications | price-fixing or anti-competitive practices | 2023 | UK-CMA | £0 |
| MT Mobility Limited | | | price-fixing or anti-competitive practices | 2014 | UK-OFT | £0 |
| MT Mobility Limited | | | price-fixing or anti-competitive practices | 2013 | UK-OFT | £0 |
| Nabuh Energy Ltd | | | energy market violation | 2020 | UK-OFGEM | £2,683,631 |
| National Grid | National Grid | utilities and power generation | energy market violation | 2016 | UK-OFGEM | £3,000,000 |
| National Grid Electricity System Operator Limited | National Grid | utilities and power generation | energy market violation | 2021 | UK-OFGEM | £1,500,000 |
| National Grid Electricity Transmission plc and Scottish Power Transmission plc | National Grid | utilities and power generation | consumer protection violation | 2021 | UK-OFGEM | £158,000,000 |
| National Grid Gas plc | National Gas Transmission PLC | utilities and power generation | energy market violation | 2011 | UK-OFGEM | £8,000,000 |
| NatWest Group | NatWest Group PLC | financial services | banking violation | 2021 | UK-CMA | £0 |
| Northside Truck & Van Limited and S.A.H. Limited | | | price-fixing or anti-competitive practices | 2013 | UK-OFT | £0 |
| npower Direct Ltd. and npower Ltd. and npower Northern Ltd. and npower Yorkshire Ltd. | E.ON | utilities and power generation | energy market violation | 2018 | UK-OFGEM | £2,400,000 |
| npower Direct Ltd. and npower Ltd. and npower Northern Ltd. and npower Yorkshire Ltd. | E.ON | utilities and power generation | energy market violation | 2014 | UK-OFGEM | £125,328 |
| Npower Group plc | E.ON | utilities and power generation | price-fixing or anti-competitive practices | 2016 | UK-CMA | £0 |
| Oakley Interiors Ltd. | | | price-fixing or anti-competitive practices | 2019 | UK-CMA | £58,558 |
| Opus Energy Limited | Drax Group PLC | utilities and power generation | energy market violation | 2012 | UK-OFGEM | £125,000 |
| OVO | | | energy market violation | 2023 | UK-OFGEM | £2,390,000 |
| Owens Installations Limited | | | price-fixing or anti-competitive practices | 2013 | UK-OFT | £1,777 |
| Oxford Publishing Limited | | | bribery | 2012 | UK-SFO | £1,895,435 |
| P&O Ferries Holdings Limited | | | price-fixing or anti-competitive practices | 2022 | UK-CMA | £0 |
| PayPoint Plc | PayPoint Group | financial services | energy market violation | 2021 | UK-OFGEM | £12,500,000 |
| Peter O'Rourke Electrical Limited | | | price-fixing or anti-competitive practices | 2013 | UK-OFT | £15,933 |
| Petrofac Limited | Petrofac Limited | oilfield services and supplies | bribery | 2021 | UK-SFO | £77,034,625 |
| Pfizer Limited | Pfizer | pharmaceuticals | price-fixing or anti-competitive practices | 2022 | UK-CMA | £63,300,000 |
| Ping Europe Limited | | | price-fixing or anti-competitive practices | 2017 | UK-CMA | £1,450,000 |
| Premier FX Limited | | | consumer protection violation | 2021 | UK-FCA | £0 |
| Premier Model Management Limited | | | price-fixing or anti-competitive practices | 2016 | UK-CMA | £150,000 |
| Prepaid Financial Services Limited | | | price-fixing or anti-competitive practices | 2022 | UK-PSR | £916,746 |
| Prestige Parking Ltd | | | price-fixing or anti-competitive practices | 2016 | UK-CAA | £0 |
| Pride Mobility Products Ltd. | | | price-fixing or anti-competitive practices | 2014 | UK-OFT | £0 |
| Prospect Estate Agency Limited and Prospect Holdings (Reading) Limited | | | price-fixing or anti-competitive practices | 2019 | UK-CMA | £268,765 |
| Protec Mobility Trading Limited | | | price-fixing or anti-competitive practices | 2013 | UK-OFT | £0 |
| Rail Assessment Centre Forum (RACF) | | | price-fixing or anti-competitive practices | 2022 | UK-ORR | £0 |
| Railway Assessment Centre Forum | | | price-fixing or anti-competitive practices | 2022 | UK-CMA | £0 |
| Rangers Football Club Limited and Rangers International Football Club Plc | | | price-fixing or anti-competitive practices | 2022 | UK-CMA | £225,000 |
| RBS Insurance Group Ltd | | | price-fixing or anti-competitive practices | 2011 | UK-OFT | £0 |
| Reckitt Benckiser Healthcare (UK) Ltd. and Reckitt Benckiser Group plc | Reckitt Benckiser | household and personal care products | price-fixing or anti-competitive practices | 2011 | UK-OFT | £10,175,000 |
| Richard Worth Limited and Richard Worth Holdings Limited | | | price-fixing or anti-competitive practices | 2019 | UK-CMA | £193,911 |
| Road Range Limited | | | price-fixing or anti-competitive practices | 2013 | UK-OFT | £115,774 |
| Roadchef Limited | Macquarie | financial services | price-fixing or anti-competitive practices | 2022 | UK-CMA | £0 |
| Robert Gregg Limited | | | price-fixing or anti-competitive practices | 2014 | UK-OFT | £0 |
| Robert Wiseman & Sons Limited and Robert Wiseman Dairies plc | | | price-fixing or anti-competitive practices | 2011 | UK-OFT | £3,200,000 |
| Robin Hood Energy Limited | | | energy market violation | 2020 | UK-OFGEM | £12,091,824 |
| Roland (U.K.) Limited and Roland Corp. | | | price-fixing or anti-competitive practices | 2021 | UK-CMA | £5,004,151 |
| Rolls-Royce PLC | Rolls-Royce | aerospace and military contracting | bribery | 2017 | UK-SFO | £510,250,000 |
| Roma Medical Aids Limited | | | price-fixing or anti-competitive practices | 2013 | UK-OFT | £0 |
| Royal Bank of Scotland Group plc | NatWest Group PLC | financial services | price-fixing or anti-competitive practices | 2011 | UK-OFT | £28,590,000 |
| Royal Mail Group plc | International Distributions Services PLC | miscellaneous services | price-fixing or anti-competitive practices | 2019 | UK-OFCOM | £0 |
