Lloyds Banking Group bosses are to be grilled by MPs over the collapse of the lender's deal to sell more than 630 branches to The Co-operative Bank.
Chief executive Antonio Horta-Osorio and chairman Sir Win Bischoff have been summoned to appear before the Treasury Select Committee next week as part of an inquiry into the failure of the deal thought to be worth £750 million.
Co-op pulled out of the branch takeover in April over fears about the strength of its banking arm's balance sheet, shortly before ratings agency Moody's downgraded it to junk status and warned it may need taxpayer support.
The deal would have transformed Co-op Bank into a major customer-owned rival to the big four high street banks, creating a lender with almost 1,000 branches and 11 million customers.
Lloyds, which has to divest the branches as an EU condition of state aid, will instead float the branches on the stock market under the TSB Bank brand.
The deal's demise has given the Government a major headache with its plans to increase banking diversity, particularly in light of Royal Bank of Scotland's failure to sell 316 branches to Santander.
Andrew Tyrie, chairman of the Treasury Select Committee, said: "This divestment should be an important opportunity to boost competition in the UK retail banking market. It could have significant benefits for consumers.
"We will want to know how The Co-operative Bank's bid was allowed to progress to such an advanced stage, why it collapsed and what will now happen to these branches and their customers."
It is thought that the Lloyds chiefs will also be questioned about whether there was any political pressure for them to originally choose the Co-op's bid over rival groups such as investment firm NBNK.
Former Co-op Group chief executive Peter Marks reportedly may also be called up before the committee.
The top 10 Fortune 500 companies
Lloyds bosses face Co-op deal quiz
Wal-Mart Stores, or Walmart, is a retailer that runs chains of discount department and warehouse stores around the world. Founded by Sam Walton in 1962, it is headquartered in Bentonville, Arkansas and has around 8,500 stores in 15 countries, under 55 different names.
Exxon Mobil Corporation, or ExxonMobil, is an oil and gas corporation formed on November 30, 1999 by the merger of Exxon and Mobil. Headquartered in Irving, Texas, it has 37 oil refineries in 21 countries.
Chevron Corporation is an energy company headquartered in San Ramon, California. It is active in more than 180 countries and is engaged in every aspect of the oil, gas, and geothermal energy industries, including exploration and generation.
Phillips 66 is a holding company - created when ConocoPhillips spun off its downstream assets - that only began trading on the New York Stock Exchange on May 1, 2012. Headquartered in Houston, Texas, the company has approximately 14,000 employees worldwide.
Berkshire Hathaway, controlled by legendary investor Warren Buffet, is a multinational holding company headquartered in Omaha, Nebraska. The company wholly owns GEICO, Dairy Queen, Fruit of the Loom and Helzberg Diamonds, as well as half of Heinz and significant minority holdings in American Express and The Coca-Cola Company.
At number 6 on the list, it's highest ever position, is iPhone and iPad manufacturer Apple. And Fortune managing editor Leigh Gallagher told CBS News that the computer giant could be even higher up the list if companies were ranked differently. Apple breaks into the top 10 for the first time this year," Gallagher said. "But if you were to rank the Fortune 500 by profits not revenues, it would be number two behind Exxon."
General Motors Company, or GM, is a multinational automotive corporation headquartered in Detroit, Michigan. It employs more than 200,000 people and manufactures the Chevrolet, Buick, Cadillac and Vauxhall brands, among others.
General Electric Company, or GE, operates in four segments: Energy, Technology Infrastructure, Capital Finance and Consumer & Industrial. Its foundation dates back to 1889, when Drexel, Morgan & Co. helped Thomas Edison to merge his many electricity-related companies to form Edison General Electric Company.
Valero Energy Corporation is the world's largest independent petroleum refiner and marketer. It has 16 refineries and 10 ethanol plants stretching from the US West and Gulf coasts to Canada, United Kingdom and the Caribbean.
Ford Motor Company (also known as Ford) is headquartered in Dearborn, Michigan, a suburb of Detroit. Founded by Henry Ford in 1903, it is still controlled by the Ford family, which now has a minority stake.