Editor's Note: A previous version of this article incorrectly referenced news from Merck KGaA. This section has been removed and replaced with pertinent information on Merck & Co. The Fool regrets the error.

The second quarter has begun with a yawn, as both the Dow Jones Industrial Average (DJINDICES:^DJI) and the S&P 500 (SNPINDEX: ^GSPC) are wavering between breakeven and a narrow gain in early afternoon trading. Both indices were up by roughly 0.3% shortly before lunchtime, trailing the Nasdaq Composite's (NASDAQINDEX: ^IXIC) 0.7% pop as the tech-heavy index's many momentum stocks continue to zig-zag wildly. Over the past month, the two larger-cap indices have been effectively flat, while the Nasdaq has diverged to the downside with a few jerky pops and drops along the way:

^DJI Chart

^DJI data by YCharts.

The first bellwether stock to report second-quarter earnings was Alcoa (NYSE:AA), the Dow's metals representative until its removal late last year. Alcoa beat analyst expectations with a $0.09 earnings-per-share print for the second quarter (Wall Street was looking for just $0.05 in EPS). The aluminum producer now expects 7% overall global growth in aluminum demand this year, which is a respectable increase in a world that continues to waver between outright growth and merely muddling through.

Surprisingly, this result, and the 3.3% pop it produced in Alcoa's shares, has not translated to major gains across the board for the Dow's industrial representatives. Boeing (NYSE: BA), which is a major user of aluminum and aluminum-based composites in its aircraft production, was up 1.5% on little news beyond Alcoa's strong showing, but no other heavy-industry Dow component has produced any real gains to speak of. The Dow's best stock has nothing to do with heavy industry at all -- pharmaceutical giant Merck (NYSE:MRK), at a 2.5% gain, is the only Dow component to move in excess of 2% just after noon. No significant news has been released by the company today, but excitement has been building around its anti-PD-1 immunotherapy drug. Merck presented early results from the clinical trials for the experimental melanoma and non-small-cell lung cancer drug at the AACR meeting recently. This could be a major driver for the company if it eventually reaches the market.

Source: Wikimedia Commons.

The S&P 500 is having a tough time trading higher because many of its components are vacillating between narrow gains and narrow losses -- only about 270 of the index's 500 stocks were in positive territory heading into the afternoon. Leading the pack is a familiar face that is also helping propel the Nasdaq today: Facebook (NASDAQ:FB) was already trading nearly 5% higher at noon thanks to two notes on the social network's shares. Susquehanna analyst Brian Nowak now has a $69 price target (down from $72) on Facebook's shares, while SunTrust analyst Robert Peck is holding steady with a $70 price target. The median analyst price target is actually higher than that, as $74 per share remains the middle ground out of a huge pool of 40 analysts polled by Thomson Reuters.

Facebook's big pop more than offsets another disappointing performance from robotic-surgery pioneer Intuitive Surgical (NASDAQ:ISRG), which has lost 6.6% today after posting first-quarter results that showed a 24% drop in year-over-year revenue. The company managed to sell barely half the surgical robots it sold in the year-ago quarter (87 against 164). It now expects to sell fewer robots in 2014 than the 546 systems it sold last year, despite recently gaining regulatory clearance for the sale of an updated system that costs about the same as properly kitted-out earlier models. Facebook's pop, on the back of a much larger market cap, produced over eight times the movement in the S&P as Intuitive's drop today.