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.

What: Shares of AcelRx Pharmaceuticals (NASDAQ:ACRX), a health care company developing the Zalviso pain-managing drug delivery system, jumped by as much as 11% today after the company confirmed its July 27 PDUFA date for Zalviso with the FDA.

So what: According to the company's press release, rumors had swirled that regulators already had approved the device -- but so far, AcelRx noted that it hasn't heard an answer over its regulatory filing for Zalviso. Investors, however, have rallied around the stock as analysts grow optimistic over an FDA approval for Zalviso. Piper Jaffrey noted last month that it expects a "timely approval" of the device around its PDUFA date, particularly after Zalviso posted strong safety and efficacy data in earlier clinical trials.

Now what: Signs are looking good for Zalviso's approval moving forward, and today's stock jump points to investor confidence in just that outcome. There's a sizable opportunity here for AcelRx: The company's drug delivery and pain-management system is aiming to compete with traditional IV-delivered pain control in hospitals, a practice AcelRx notes can lead to infections, human errors, and other potential hazards.

Zalviso has already won its share of supporters. AcelRx inked a deal worth up to $250 million to sell the system's European and Australian rights to German company Grunenthal GmbH, and Piper Jaffray foresees up to $300 million to $400 million in peak U.S. sales for the system if approved.