The Dow Jones Industrial Average (DJINDICES:^DJI) kicked off the week with a move to the downside, shedding more than 40 points as of 11:30 a.m. EST. Dow component Microsoft (NASDAQ:MSFT) led the index lower, falling nearly 2% in early trading. Other tech stocks were mixed, with Twitter (NYSE:TWTR) notching another notable decline while shares of chip maker NVIDIA (NASDAQ:NVDA) got a slight boost.

ISM nonmanufacturing PMI disappoints
The Dow Jones' sell-off may have prompted by disappointing Institute for Supply Management nonmanufacturing PMI data. The index, which measures the strength of the nonmanufacturing segment of the U.S. economy, came in at a reading of 53, while economists had anticipated a 54.5 reading. Still, there's reason to be hopeful: Any ISM reading of more than 50 indicates economic expansion. Monday's data, however, shows the expansion isn't as great as some expected.

Can Microsoft find a new CEO?
Microsoft's sell-off was pretty substantial for a company with a market cap of more than $300 billion. Investors were likely selling Microsoft shares in the wake of a Wall Street Journal report that it is taking the company longer to find its next CEO than it had anticipated. With both current CEO Steve Ballmer and Microsoft founder Bill Gates likely to stay on the board, would-be CEOs could have a difficult time managing the company.

Twitter hit with another downgrade
Microsoft's drop was tame compared to Twitter's -- the high-flying social media IPO was down nearly 5% early on Monday after yet another stock downgrade. This time, Morgan Stanley cut its rating on the stock to underweight with a $33 price target. Morgan Stanley believes that Twitter's success is far from guaranteed. It will have to compete fiercely with other social media giants for ad dollars; while Twitter could win out, Morgan Stanley thinks the risk/reward profile is far from attractive.

NVIDIA enters the car market
NVIDIA's stock, meanwhile, was up more than 0.80%. Admittedly, that isn't a huge gain for a company with just a $9 billion market cap, but there was some relatively big news for NVIDIA investors. During its presentation at the Consumer Electronics Show in Las Vegas, NVIDIA unveiled some new mobile chips, including a Tegra K1 graphics chip.

NVIDIA also landed a deal to supply chips to car makers. In the years to come, many cars with center consoles powered by the Android operating system could sport NVIDIA chips.