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

Investors can expect a weak start to the stock market today, as the Dow Jones Industrial Average (^DJI 0.23%) lost 71 points, or 0.5%, in premarket trading. Global shares fell in overnight trading, led by a 1.8% drop in Japan's Nikkei index. Federal Reserve Chairwoman Janet Yellen's second day of testimony to Congress, which was set for today, has been postponed on account of the winter storm blanketing the Washington, D.C. region.

Meanwhile, news is breaking this morning on several stocks that could see heavy trading in today's session, including Time Warner Cable (NYSE: TWC), Discovery Communications (DISC.A), and Goodyear Tire & Rubber (GT -1.26%).

Time Warner Cable is being acquired, but not by Charter Communications (CHTR -0.26%). Instead, Comcast (CMCSA -0.12%) has agreed to purchase the nation's second largest cable company in an all stock deal valued at $45 billion, the two announced this morning. Time Warner shareholders will receive $159 per share of stock in the combined company, almost exactly what the cable operator's management had said Time Warner was worth. Charter had bid closer to $130 a share. Time Warner's stock is up 11% in premarket trading, while Charter's stock is down 8%.

Discovery Communications today posted fourth-quarter earnings results in which sales jumped by 28%, to $1.5 billion. That bounce was driven by growth in its international business, which improved by 64% while its U.S. networks ticked higher by a more modest 5%. Adjusted profit grew to $0.92 a share, slightly ahead of the $0.89 that analysts had targeted. Discovery provided a strong outlook for 2014, saying sales should improve by about 20% to as much as $6.6 billion. The stock is down 1.2% in premarket trading.

Finally, Goodyear this morning announced that revenue fell by 5% last quarter, to $4.8 billion. The company saw tire unit volume tick higher by 2%, but that growth was overwhelmed by a big drop in chemical sales. Still, profitability improved as the company logged a record $419 million of operating income, up 54% on price increases. This led to an almost doubling of operating margin in the U.S., to 9.3%. Goodyear also affirmed its guidance for 2014, saying that sales volume should improve by between 2% and 3%, powering a 10%-15% rise in profit. The stock is up 2% in premarket trading.