Congratulations, Pharmasset (Nasdaq: VRUS) investors, you almost pulled off an overnight double as Gilead Sciences (Nasdaq: GILD) fired a shot across the bow of other hepatitis C drug makers.

For $11 billion, a 59% premium above Pharmasset's all-time high, Gilead is getting PSI-7977, an oral treatment that doesn't require interferon injections and their nasty side effects. This is potentially a huge improvement over the current standard of care, such as recently approved drugs like Vertex Pharmaceuticals' (Nasdaq: VRTX) Incivek and Merck's (NYSE: MRK) Victrelis.

It's no surprise that Vertex is down 3% as of this writing and that Inhibitex (Nasdaq: INHX), with its oral hep-C candidate INX-189, is up 25%. INX-189 has shown excellent data so far, but it hasn't entered phase 3 trials yet. Oddly, Achillion (Nasdaq: ACHN), with three hep-C drugs in development, is up only 3%, but the stock saw shares pop last week when the company's CEO got the market excited about a potential buyout. And on a day when the Dow Jones Industrial Average (INDEX: ^DJI) is down 316 points, being up is no small feat.

For Gilead, this is not an indictment of its own stable of hep-C drug candidates. The future of treatment of this disease will be drug cocktails, similar to Gilead's HIV treatments Atripla and the upcoming Quad. Pharmasset already had deals with Bristol-Myers Squibb and Johnson & Johnson to create combo products. Now Gilead will potentially get a cut of those products' sales, and also the chance to boost its own higher-margin offerings' chances of success.

The multibillion-dollar race for hepatitis C treatment supremacy is well under way. The best way to track the latest developments surrounding the companies mentioned above is to add them to our free My Watchlist feature:

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