For months, the rule on Wall Street has been to buy any dip you're fortunate enough to get. That strategy has worked again this morning as positive earnings reports and a modest rebound in Europe helped allay yesterday's fears that a plunge back into economic crisis was imminent. The prospect of merger and acquisition activity is looking up after Dell (UNKNOWN:DELL.DL) succeeded in making a going-private deal that will pay shareholders $13.65 per share in cash. This move, too, has helped push the market higher, and by 11 a.m. EST the Dow Jones Industrials (DJINDICES:^DJI) managed to climb 120 points back up to 14,000.

Leading the Dow higher is Bank of America (NYSE:BAC), which climbed more than 2.9% in early trading. Optimism about the stock has climbed as money manager Bruce Berkowitz has been noted the bank's potential for huge returns in the coming years. With B of A trading well below book value and prospects for the industry improving, Berkowitz thinks he could end up quadrupling his money on Bank of America if conditions in banking return to their historical norms.

Speaking of B of A, Zynga (NASDAQ:ZNGA) rose more than 4% after getting a somewhat surprising analyst upgrade from the bank's Merrill Lynch unit. The social-gaming company doesn't report until after the close today, but the analyst thinks stabilizing mobile trends, the potential for higher-than-expected bookings, and the relative performance of other social stocks justify the upgrade.

Finally, SandRidge Energy (NYSE:SD) fell another 3.8%, building on substantial losses over the previous two trading days. The company's spun-off Mississippian royalty trusts have posted disappointing results, calling into question SandRidge's overall strategy. With guidance on those trusts raising concerns about future growth and production, SandRidge needs to re-establish that its reliance on the Mississippian Lime will pan out, rather than leaving investors exposed to high risks.

Fool contributor Dan Caplinger has no position in any stocks mentioned. You can follow him on Twitter @DanCaplinger. The Motley Fool owns shares of Bank of America. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.