NEW YORK (Reuters) - Stocks closed mostly flat on Tuesday after volatility late in the session, with weakness in materials and energy shares offsetting strength in financials. Shares traded higher for much of the session on the back of an unexpectedly strong read on existing home sales, which lifted banks. But those gains dissipated in the last half hour of trading, with Wall Street briefly turning solidly negative before staging a rebound. ...

NEW YORK (Reuters) - Former Goldman Sachs director Rajat Gupta was once on hedge fund billionaire Raj Rajaratnam's "important people" list but excluded from a fantasy football celebration helicopter trip to Atlantic City with other corporate high-flyers. On the second day of Gupta's insider-trading trial in Manhattan federal court on Tuesday, prosecutors tried to establish for the jury his ties to now-imprisoned Rajaratnam, while defense lawyers sought to describe some distance between the men. Gupta, 63, is the most prominent corporate figure indicted in a broad U.S. ...

(Reuters) - Two top U.S. financial regulators said on Tuesday the issues around the initial public offering of Facebook should be reviewed, putting fresh pressure on the company, its lead underwriter, Morgan Stanley, and the Nasdaq stock exchange. Facebook shares closed 8.9 percent lower at $31, following an 11 percent plunge on Monday. At that price the company has shed more than $19 billion in market capitalization from its $38-per-share offering price last week. ...

WASHINGTON (Reuters) - Wanted for the Treasury Department: a new boss who can fix trillion-dollar-plus budget deficits, overhaul the tax system and spur a reluctant Europe into fixing its debt crisis. It's a tall order, especially when the new Treasury chief also must deal with a fractious Congress - and all for a salary lower than that paid to many junior Wall Street bankers. ...

SHANGHAI (Reuters) - China is rolling out sweeping brokerage reforms to nurture future global investment banks that officials hope could eventually compete with the likes of Goldman Sachs and Morgan Stanley , a regulatory document showed. The China Securities Regulatory Commission wants to allow domestic brokerages, which now get most of their money from trading stocks and underwriting new securities, to expand in futures and derivatives, asset management, private banking and private equity, according to a commission document distributed to securities firms earlier in the month. ...