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.

The Dow Jones Industrial Average (DJINDICES:^DJI) looks set to stumble out of the gate this morning. Stock index futures as of 7:20 a.m. EDT indicate a 0.23% fall despite European economic data showing a return to growth following six consecutive quarters of contraction. Eurozone exchanges didn't spike on the news, either.

Instead, volatility amid light volume looks like the prescription for today, continuing a trend we've seen over the last few trading days. On Tuesday, the Dow bounced from gains to losses and back, trading near a one-month low early in the session before jumping up to close higher by 0.2%.

But today it's a safe bet that Wall Street will have its gaze fixed on a stock that's not among the Dow's 30: Apple (NASDAQ:AAPL). The tech giant's shares have been rising all week, beginning with reports on Monday about the coming launch of a new iPhone model. Yesterday the rally continued, but for different reasons. Shares leapt 5% higher after activist investor Carl Icahn announced having established a position in the Mac maker that The Wall Street Journal tallied at a hefty $1.5 billion. Apple's market cap quickly surged by multiples of that figure after Icahn's announcement, spiking by $17 billion. In premarket trading, Apple is up about 1%, flirting with the $500 per-share mark, which it hasn't seen since January -- but if you believe Icahn, the shares are worth at least $625 apiece.

Outside of the tech sector, transportation stocks could see more activity in the wake of yesterday's news that the U.S. Department of Justice is challenging the proposed merger between US Airways and American Airlines. Airline stocks saw intense selling pressure and got cheaper across the board yesterday, but investors interested in the sector may want to wait for the dust to settle before jumping in.

Finally, Macy's (NYSE:M) looks poised to drop almost 3% at the open after announcing second-quarter sales that it admits were "softer than anticipated." The retailer notched profit of $0.72 per share and sales that fell 0.8% to $6.07 billion, falling short of analysts' expectations of $0.78 in EPS and $6.25 billion in revenue.