We are in the thick of earnings season, a deal was made in D.C. and stocks are challenging new all-time highs almost daily. So how do investors know which stocks to buy and which ones to sell? 24/7 Wall St. reviews dozens of Wall Street analyst research reports each and every morning looking for new ideas for our readers. Some are stocks to buy, some are stocks to sell or avoid, and some are strategic calls broken out individually. These are this Tuesday’s top analyst upgrades, downgrades and initiations seen from Wall Street research firms.

AbbVie Inc. (NYSE: ABBV) was reiterated as Buy and on the Focus List, and the price target was raised to $59 from $52, at Argus.

Altra Holdings Inc. (NASDAQ: AIMC) was raised to Buy from Neutral at Bank of America Merrill Lynch.

American Capital Agency Corp (NASDAQ: AGNC) was downgraded to Neutral from Buy at Bank of America Merrill Lynch.

Apple Inc. (NASDAQ: AAPL) was raised to Outperform from Neutral at R.W. Baird, was reiterated Buy and the price target was raised to $610 from $540 at Argus, maintained Neutral at Credit Suisse and maintained at Outperform and raised price target to $560 from $540 at Oppenheimer.

Banco Bilbao Vizcaya Argentaria S.A. (NYSE: BBVA) was downgraded to Underperform from Neutral at Bank of America Merrill Lynch and downgraded to Neutral from Outperform at Credit Suisse.

Chubb Corp. (NYSE: CB) was reiterated as Buy and on the Focus List, and the price target was raised to $102 from $95, at Argus.

Dollar General Corp. (NYSE: DG) was started as Positive at Susquehanna (a late Monday call).

Michael Kors Ltd. (NYSE: KORS) was downgraded to Market Perform from Outperform at Wells Fargo.

Northeast Utilities (NYSE: NU) was started with an Outperform rating and a $47 price target at Credit Suisse.

PotBelly Corp. (NASDAQ: PBPB) was started as Neutral at Goldman Sachs, started as Market Perform at William Blair and started as Overweight at Piper Jaffray.

SeaDrill Ltd. (NYSE: SDRL) was downgraded to Sell from an already cautious Hold rating at Soc-Gen.

Susquehanna Bancshares Inc. (NASDAQ: SUSQ) was raised to Buy from Neutral at Sterne Agee.

Volcano Corp. (NASDAQ: VOLC) has spewed all over itself after poor guidance ahead, sending shares down over 15%. We have seen downgrades from Canaccord Genuity, J.P. Morgan and Credit Suisse, with others likely.

Webster Financial Corp. (NYSE: WBS) was downgraded to Neutral from Buy at Sterne Agee.

Yahoo! Inc. (NASDAQ: YHOO) was raised to Outperform from Market Perform by Bernstein.