The stock market mostly treaded water on Wednesday, as investors were largely content to wait and see what comes next for the U.S. economy. The Federal Reserve concluded its two-day meeting earlier in the afternoon, deciding to leave rates unchanged but announcing the general format that it will follow in starting to allow its balance sheet to shrink from its currently level of about $4.5 trillion. Some investors are concerned that the Fed's move will amount to a tightening that could slow economic growth, but most market participants seemed satisfied that the central bank will be slow in its movements. Most major benchmarks finished in the green, and a few stocks managed to post even better gains. BlackBerry (NYSE:BB), Plug Power (NASDAQ:PLUG), and USG (NYSE:USG) were among the best performers on the day. Below, we'll look more closely at these stocks to tell you why they did so well.

BlackBerry races ahead with autonomous vehicles

Shares of BlackBerry climbed 8% on news that the mobile device company will work with a major player in the automotive sector toward the goal of coming up with an autonomous driving system. Delphi Automotive (NYSE:DLPH) said that it had signed an agreement with BlackBerry under which the smartphone pioneer will provide the operating system for Delphi's self-driving system, with the goal of improving software performance in order to make the vehicles safer. One BlackBerry executive noted that with cybersecurity threats to self-driving vehicles, "[I]t is imperative that auto manufacturers are provided with software that is safety certified, reliable, and secure." BlackBerry can do so, and that could give it an edge against rivals as the race to autonomous cars continues.

Black mobile device from BlackBerry.

Image source: BlackBerry.

Plug Power keeps powering up on insider bullishness

Plug Power stock jumped another 14%, adding to gains after a key company insider made a substantial purchase of the fuel-cell specialist's shares. Board chair George McNamee bought 200,000 shares of Plug Power stock, spending more than $425,000 and boosting his position by nearly half. The fuel-cell company's stock has been volatile, with excitement about new deals with major retail players giving way to pullbacks as hoped-for follow-on deals have been slow in coming. Until its partnerships result in actual rising sales and profits, Plug Power will have trouble building up forward momentum.

USG hopes for a building boom

Finally, shares of USG gained 6%. Bullish investors in the sheetrock and building materials specialist have been enthusiastic about the potential for USG to benefit from a big rise in demand following major hurricanes in two different regions of the U.S. market. Even before the widespread destruction in the path of those storms, USG had the potential to benefit tremendously from proposed new projects promoting infrastructure development. One potential pitfalls stems from the shortage of labor to perform needed rebuilding projects in those areas hardest hit by the hurricanes, and that could draw out any gains that materials providers like USG reap. Nevertheless, in the long run, any rebuilding effort should be positive for USG, and that in turn should trickle down to shareholders in time.

Dan Caplinger has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.