Wall Street brokers and investors came to the rescue of key broker Knight Capital Group with a $400 injection to counter losses on a computer trading error, Knight announced Monday. Knight said Jefferies Group, Blackstone, Stifel Financial Corp., TD Ameritrade and others would get preferred shares convertible to common stock for their emergency injection, which would help the company survive huge losses on the glitch. The mishap, which caused the firm to unintentionally buy and sell millions of shares in over 100 companies, rattled the New York Stock Exchange at the opening of trade on Wednesday. Knight said Thursday that unwinding the trades cost the firm $440 million and had \"severely impacted\" its capital base, forcing it to seek fresh outside funds. A key player on electronic markets, Knight says it executes around 219 million share trades per day using sophisticated trading technology. Tom Joyce, Knight\'s chairman and chief executive, said the support demonstrated the company\'s importance to Wall Street. \"Knight\'s financial position and capital base have been restored to a level that more than offsets the loss incurred last week,\" Joyce said in a statement. \"The array of participants in this capital infusion underscores Knight\'s critical role in the capital markets. \"With our financial positions strengthened and liquidity restored, we will continue to provide clients with trading in a broad range of securities, high-quality execution and outstanding client service.\" Knight\'s shares were down 22.5 percent to $3.14 in morning trade Monday as investors sold the company down in reaction to the terms of the rescue deal. The shares closed last Tuesday, the day before the problem erupted, at $10.33. Earlier this year Knight was one of the strongest critics of the Nasdaq exchange\'s computer glitches that fouled up the launch of Facebook shares on the exchange. Knight called for $35 million in compensation from Nasdaq for losses it claimed from the launch, which mainly hit a number of electronic, program-based traders when Facebook shares went public on May 18.