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.

Stocks tumbled today as investors reacted to the next step in the Federal Reserve's stimulus taper, with the central bank announcing at 2 p.m. ET that it will cut another $10 billion of its monthly bond-buying program, lowering the total to $65 billion. The market had traded down all session long but took a noticeable dive lower after the announcement as the Dow Jones Industrial Average (DJINDICES:^DJI) dropped 190 points or 1.2%, while all three major indexes fell 1% or more. The market's reaction was the reverse of what we saw from the Fed's surprise taper in December, when stocks soared as the Fed said it would begin cutting its quantitative easing program. Back then, investors seemed more confident about the economic recovery, as the country had just come off two strong jobs reports. However, with last week's emerging-market currency crisis, caused in part by shifting interest rates in currency values to the Fed's program, investors are clearly feeling more jittery this time around.

Concerns about the Fed overshadowed earnings from major companies such as Boeing (NYSE:BA), which slid on a weak forecast, closing the day down 5%. The manufacturing giant crushed it in the quarter gone by, with per-share profits of $1.88 against estimates of $1.57, and revenues increased 6.6% to $23.8 billion, well ahead of the consensus at $22.5 billion. Still, guidance was light, as the airplane-maker sees a 2014 EPS of $7.00-$7.20, short of the Street's view at $7.48, though the company is known for conservative guidance. While Boeing continues to score major contracts and add to its record backlog, perhaps the stock was ready for a breather after it nearly doubled in 2013.

After hours, Facebook (NASDAQ:FB) soared 12% on yet another blockbuster quarterly report as profits and revenue both soared. The social-networking giant said adjusted per-share earnings jumped from $0.17 to $0.31, beating estimates of $0.27, while revenue surged 63% to $2.59 billion, topping expectations at $2.35 billion. Mobile usage, a key to the company's future was strong as monthly mobile users grew 39% and daily mobile users were up 49%. The report is a boon not just for Facebook, but for all social-media stocks, as the company's skyrocketing growth shows the huge potential for the new online medium. Twitter, for example, was up 6% on the news.