Why are Gilead Sciences (NASDAQ:GILD) shares falling?

Gilead Sciences, Inc. (Public, NASDAQ:GILD) reported earnings yesterday, but the blow-out-quarter doesn't seem to be impressing investors today, as shares are down 3%.

Here is a summary of the call:

* Net profit 72 cents/share beats 67 cents/share estimate

* Revenue increases 31 pct to $1.8 billion

Gilead Sciences Inc said on Tuesday its quarterly profit rose 36 percent, due in part to royalties on sales of the flu drug, Tamiflu, but sales of its core HIV drugs failed to impress investors and its shares fell 2.3 percent after hours.

Gilead posted a third-quarter net profit of $673 million, or 72 cents per share, compared with $495.9 million, or 52 cents per share, a year earlier.

The results beat the average analyst forecast of 67 cents a share, according to Thomson Reuters I/B/E/S.

Quarterly revenue rose 31 percent to $1.8 billion and product sales rose 23 percent to $1.65 billion.

Sales of AIDS drug Truvada rose 13 percent to $620.6 million, but fell short of the Wall Street consensus of $626 million, as compiled by Wedbush Morgan Securities.

Third-quarters sale of Atripla, which combines Truvada with Bristol-Myers Squibb Co's (BMY.N) Sustiva into a single pill, rose 42 percent to $605.3 million, meeting analysts' expectations.

Royalty, contract and other revenue nearly quintupled to $152.4 million. Gilead gets most of its royalty revenue from Roche Holding AG's (ROG.VX) sales of Tamiflu, which has seen strong demand because of the swine flu pandemic.

REALLY? Revenue increases 31 pct, but investors are bailing because the AIDS drug Truvada grossed $620.6M instead of $626M, falling short by just $6M?

Fellow Stockmasters, this is a special situation and a great opportunity to get in on shares of GILD for value. Tamiflu is just gravy, and you need to get on the gravy train.