The markets remain mixed as the big indexes essentially flip-flopped from their Monday close. Retail sales came in better than anticipated, but despite totally reversing course, up 0.8% versus June's 0.7% decline, it still couldn't get investors excited. Of course, talk that Greece is looking for a two-year austerity extension threw a wet blanket on any enthusiasm. Tomorrow's inflation data could move the markets, but August tends to be a slow month, so all but the largest headlines may fail to find traction.

The Dow Jones Industrial Average (INDEX: ^DJI), finished up just 2 points, or 0.02%, the near definition of flat -- but not to be outdone, the S&P 500 managed to move only 0.01% to the downside. The Nasdaq was our heavy lifter today, losing an incredible 0.2%. Feel the volatility!

On the Dow, we saw a large 3.6% gain from Home Depot (NYSE: HD), which not only beat estimates but raised guidance as well, giving investors confidence that the housing recovery will continue. Bank of America (NYSE: BAC) shares, meanwhile, were up 0.8% on no real news, but the stock continues to be a favorite among traders. Today alone, 104 million shares traded hands, the most of any stock on or off the Dow, but amazingly that's still significantly under the company's three-month average volume of 160 million shares. If you are thinking of investing in B of A, make sure you're prepared for the daily volatility that comes with its current status.

The biggest gainer on the Nasdaq was Arena Pharmaceuticals (Nasdaq: ARNA), closing up 15% on talk that Big Pharma was stalking the small biotech as a takeover candidate. Arena already has a marketing deal with Eisai, but that isn't enough to scare off a motivated buyer. I would be slightly surprised if Arena, or for that matter, its competitor VIVUS (Nasdaq: VVUS), which rose on the news, get taken out before a would-be acquirer can see how doctors are prescribing their respective drugs. Sure, it will cost more at that point, but I would rather pay a premium for a good product than get a deal on a dud.

Investing opportunities abound in the biotech world. Find out more about one company getting a lot of attention recently in The Motley Fool's new premium report on Arena Pharmaceuticals. This report outlines key opportunities and risks facing the company, plus the must-watch areas for investors. Get your copy now!

David Williamson holds no position in any company mentioned. Check out his holdings and a short bio. The Motley Fool owns shares of Bank of America. Motley Fool newsletter services have recommended buying shares of The Home Depot. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. Try any of our Foolish newsletter services free for 30 days. The Motley Fool has a disclosure policy.