Traders moved more shares of Bank of America ( BAC) and Citigroup ( C) than any other company as investors turned bullish on financial services stocks, an industry that has earned low grades from TheStreet.com Ratings. Of the 25 stocks and exchange traded funds with the largest trading volume in the U.S. yesterday, 11 were tied to finance. Among those, six have "sell"-level grades of D-plus or lower, suggesting they might offer more risk than return potential. Investors are trying to follow the direction of financial companies' fortunes. John Mack, chief executive officer of Morgan Stanley ( MS), said 2009 would be a difficult year, and JPMorgan ( JPM) and Bank of America had said March wouldn't turn out as good as January and February. Those comments followed Citigroup CEO Vikram Pandit's assessment in early March that the bank was profitable in January and February, sending financial shares soaring. Still, the S&P 500 Financials Index jumped 6.7% yesterday. Wells Fargo ( WFC), American International Group ( AIG) and the Financial Select Sector SPDR Fund ( XLF) ranked among the day's 10 most-active securities. Interest in financial stocks and ETFs is high as investors anticipate the potential for new regulations and accounting rules. World leaders will meet later this week for the Group of 20 summit, where reversing the global recession will be at the top of the agenda. Investors are also weighing proposed changes to "mark-to-market" accounting rules, which dictate how banks must value assets. The Financial Accounting Standards Board is expected to make a decision this week on adjustments that could help boost banks' profits. The ProShares UltraShort S&P 500 ( SDS) was the only "buy"-rated security on the list, ranking 25th. The fund is designed to deliver the opposite performance of the S&P 500 Index. General Motors ( GM), the 22nd most-traded stock, holds the lowest grade of the group, E-plus. The company's shares fell 28% yesterday. New Chief Executive Officer Fritz Henderson said bankruptcy was becoming more probable. According to a published report, President Barack Obama believes a pre-packaged bankruptcy is the most likely way for General Motors to restructure.