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.

November's second full day of trading saw stocks rise yet again, a continuation of the stubbornly optimistic bullish trend seen in the markets since the woeful lows of March 2009. Most Americans remember how bad tough things were during the financial crisis, but every now and then it helps to put things in perspective. The S&P 500 Index (SNPINDEX:^GSPC), for instance, has rallied more than 160% since the troughs of 2009 more than four years ago. That depressed level -- the S&P closed just above 676 on March 9, 2009 -- hadn't previously been seen since Bill Clinton's first term as president. Putting talks of a current market bubble aside for a moment, let's be thankful that the economy is now in a better state of affairs. The stock market certainly seems to agree, and the S&P added 6 points, or 0.4%, to end at 1,767 today. 

Santa Clara, Calif.-based semiconductor company NVIDIA (NASDAQ:NVDA) slumped 2.9% Monday, as shares were hit by a price target decrease from Wall Street research firm RBC. The company is set to announce quarterly earnings Thursday, so a bit of pre-earnings volatility is to be expected. But with NVIDIA losing some of Apple's coveted accounts recently, shareholders can't just sit back and snooze on this company. Keep a close eye on the inroads NVIDIA makes in the mobile chip market going forward, as successful diversification into that arena could mean a big win for investors.

Biotech giant Gilead Sciences (NASDAQ:GILD) fell 2.3% today, also bucking the bullish trend of the markets. Both $106 billion Gilead and our final laggard of the day, Vertex Pharmaceuticals (NASDAQ:VRTX), are in the hepatitis-C treatment business. Vertex Pharmaceuticals, by virtue of its much smaller size, has fewer resources to compete with. Vertex is still worth $15 billion on the open market, but shares lost 1.7%, and have shed 15% in the past week alone, as it struggles to deal with rapidly declining sales of its hepatitis-C drug, Incivek. 

With Gilead's own hepatitis-C product expected to be approved by the FDA, Vertex cut its sales force by 15% as it refocuses its efforts on its cystic fibrosis treatment, Kalydeco. That said, Gilead doesn't have the future Hepatitis C market all to itself: Its drug, sofosbuvir, is expected to go head-to-head with Johnson & Johnson's simeprevir.