Although we don't believe in timing the market or panicking over daily movements, we do like to keep an eye on market changes -- just in case they're material to our investing thesis.

In the tug of war among stock investors, all it takes is a couple of good days to completely change prevailing sentiment. Today's gains in broad-market indexes pulled the S&P 500 to the break-even point for 2014, as positive earnings news from Bank of America continued the string of optimistic reports from the financial sector that we've seen this week. Yet the gains in Mattress Firm (NASDAQ:MFRM), DryShips (NASDAQ:DRYS), and Thompson Creek Metals (OTC:TCPTF) easily eclipsed the solid gains from the broader market.

Mattress Firm soared 15% after reports surfaced that it could seek to buy out rival chain Sleep Train. Adding California-based Sleep Train would add to Mattress Firm's national reach, making it an even bigger force to be reckoned with in the fragmented mattress-retail business. Meanwhile, with the success of mattress producer Tempur Sealy (NYSE:TPX) and its combination of its high-end Tempur-Pedic and more mainstream Sealy mattresses, Mattress Firm has done a good job of identifying the common denominator in giving customers what they want for their bedding.

DryShips gained 9% on a good day for shipping stocks generally, bouncing back from a terrible start to 2014. Volatility in shipping rates has caused many investors to lose confidence in the potential for the shipping industry to keep rebounding following a highly positive 2013. Yet as further signs of economic progress start to emerge both within the U.S. and around the world, hopes that the long-suffering glut of shipping capacity will finally start to dissipate could send DryShips and its peers on another leg up in 2014 -- as long as the recovery doesn't falter.

Thompson Creek Metals rose another 12% today, bringing its two-day gain to 32%. The mining company's positive news both from its molybdenum production figures for the full year as well as early results from its Mt. Milligan copper and gold mine have reawakened enthusiasm about Thompson Creek's prospects, especially after the stock lost almost half its value last year. At this point, Mt. Milligan is only getting to the point at which it will reach 60% of operating design capacity for a 30-day period. Further ramping up could bring even further production growth to the mine, and with strength in copper prices recently, the results could be coming at a perfect time for Thompson Creek investors.