It was another day of mixed data for the broad-based S&P 500 (SNPINDEX:^GSPC), but this time investors were able to look past recent housing weakness and latch on to improved consumer outlooks.

The big driver today was the Conference Board's final consumer confidence reading for March, which at 82.3 marks a six-year high. This improvement from a prior reading of 78.3 moves us decisively past the winter swoon that brought confidence levels down and signals that consumers are considerably more optimistic about their short-term and long-term financial outlooks. This reading is noteworthy since consumer spending accounts for roughly 70% of U.S. GDP.

On the flip side, housing data continued to be a modest disappointment. Although the Case-Shiller 20-city index showed a 13.2% year-over-year improvement in home prices thanks to tight inventory controls from America's top homebuilders, new homes sales fell by more than 3% in February to a seasonally adjusted annual rate of 440,000. There's only so much inventory tightening that homebuilders can do before volume begins to outweigh higher prices and negatively affects their bottom line.

By day's end the S&P 500 put its two-day losing streak in the rearview mirror and pushed decisively higher by 8.18 points (0.44%) to close at 1,865.62.

Source: Plug Power.

Leading the pack higher today was highly polarizing fuel-cell systems developer Plug Power (NASDAQ:PLUG). which exploded to the upside by 49% after CEO Andy Marsh told MarketWatch in a telephone interview on Tuesday that the company had signed an additional order with a global automaker that should be announced in the next two to three weeks. The report also noted that Plug Power anticipates landing another GenKey deal this year similar to the one it signed with Wal-Mart earlier to supply 1,738 fuel-cell systems for forklifts in six regional warehouses. While I continue to applaud Plug Power for validating its technology through these large deals, I very much believe that shareholders are counting their chickens before they're hatched. We have no details about this auto deal and Plug still isn't profitable on a trailing basis. I'd much prefer to wait for these uncertainties to clear before even considering it a viable investment.

Varonis Systems (NASDAQ:VRNS), which makes software that enables businesses to manage and analyze their unstructured data, gained 19.9% after the expiration of the lockup period allowed five research firms to initiate coverage on the company. In total, Varonis received three buy rating equivalents from RBC Capital, Needham, and Jefferies, which respectively initiated price targets of $50, $48, and $45. As a reminder, Varonis' shares closed yesterday at just $36.51. It also received two ratings that were the equivalent of a hold from Morgan Stanley and Barclays. I personally tend to fall more in line with Morgan Stanley and Barclays in that I recognize the high-growth opportunity afforded to Varonis, but believe profit may be a ways off as it sacrifices bottom-line gains for research and development and expansion.

Source: Galectin Therapeutics.

Lastly, clinical-stage biopharmaceutical company Galectin Therapeutics (NASDAQ:GALT) jumped 8.8% after issuing a press release noting that it would announce the first part of its phase 1 results for GR-MD-02 in patients with nonalcoholic steatohepatitis, or NASH, with advanced fibrosis on Monday, March 31. The press release noted that CEO Peter Traber would hold a webcast to discuss the results the following day. Investors have to be thinking here that the data is positive, otherwise it seems very unlikely that Galectin would schedule a webcast. All eyes are on GR-MD-92, since NASH is a widespread disease estimated to affect 6 million people in its most severe form. But this phase 1 data is merely based on safety and biomarker identification and is unlikely to reveal much in the way of drug efficacy. Shareholders would be best suited sticking to the sidelines until we have more concrete efficacy data from later-stage studies.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.