Schneiderman, in a press conference on Wednesday, argued Barclays falsely marketed its dark pool as being safe from what its internal marketing materials described as "predatory," "aggressive," and "toxic" activity by high-frequency traders.

The complaint cited internal emails in which Barclays employees deliberately withheld or changed information about its dark pool to make it appear safer and more attractive to prospective clients such as mutual funds.

5. -- GoPro, the maker of wearable sports cameras, said late Wednesday it sold 17.8 million shares at $24 each in its initial public offering of stock.

The IPO was priced at the high end of GoPro's expected range and raised $427 million, valuing the whole company at about $3 billion. 

The stock will begin trading on Nasdaq Thursday under ticker symbol " (GPRO)."

6. -- Hedge fund Paulson & Co. has amassed a large stake in Allergan (AGN) of more than 6 million shares and supports a deal between the Botox maker and Valeant Pharmaceuticals  (VRX), people familiar with the matter told Reuters.

The position is expected to make the U.S. hedge fund, led by John Paulson, one of the top 10 to 15 holders of Allergan, according to Thomson Reuters shareholder data as of March 31.

Paulson's new position in Allergan could give Valeant a boost, as the company tries to drum up support from at least 25% of Allergan shareholders so that it can call a special meeting, Reuters said. Valeant and Bill Ackman's Pershing Square Capital Management are seeking to call a meeting to elect new directors to Allergan's board, which could pave the way for a takeover of the company.

7. -- London Stock Exchange agreed to acquire Frank Russell Co., owner of Russell Investments, for $2.7 billion from Northwestern Mutual Life Insurance

The deal would represent the LSE's largest acquisition since it bought the remaining 50% stake in FTSE International, known for the U.K.'s FTSE 100 Index, from Pearson in 2011, according to The Wall Street Journal.

The purchase of Frank Russell, which operates the Russell 2000 Index, will help LSE expand its index and exchange-traded fund businesses.

8. -- Wall Street expects sneaker and athletic apparel maker Nike (NKE) to post fourth-quarter earnings on Thursday of 75 cents a share on revenue of $7.34 billion.

9. -- Bed Bath & Beyond (BBBY) reported fiscal first-quarter earnings that were short of analysts' expectations.

The retailer reported earnings 0f 93 cents a share, where were 2 cents below forecasts. Revenue of $2.66 billion was also $30 million short of the $2.69 billion consensus estimate.

Bed Bath & Beyond issued second-quarter guidance of $1.08 to $1.16 a share, less than the $1.20 analysts are expecting.

10. -- General Motors (GM) told dealers in the U.S. and Canada to stop selling 2013 and 2014 Chevrolet Cruze sedans because of a potential defect in air bags made by air bag supplier Takata.

"Certain vehicles may be equipped with a suspect driver's air bag inflator module that may have been assembled with an incorrect part," GM spokesmen Jim Cain said in a statement. "We are working diligently with the supplier of the defective part to identify specific vehicles affected and expect to resume deliveries by the end of this week once those vehicles are identified."

GM, which notified dealers of the stop-sale order on Tuesday, said it has identified about 33,000 Cruze sedans, mostly in the U.S. and Canada, that may have been built with parts from the bad batch and said it believes it is close to identifying all the problem cars, USA Today reported.