It's a good day for Starbucks' chief executive, Howard Schultz, as one vulture, at least, has given up circling: Fast-food baron and activist investor Nelson Peltz has dumped his stake in Starbucks.

News that the activist investor's interest has waned sent Starbucks stock up almost 5 percent in afternoon trading today, as the move seems to signal that Peltz feels the company is getting back on track on its own.

Peltz's Trian Fund Management disclosed in May that it had bought 898,500 shares of Starbucks (which represents less than 1 percent of outstanding shares)—potentially disturbing news for the coffee chain's executives, given Peltz's reputation for buying into companies (Heinz, Wendy's, Cadbury) and pressuring the management into changes.

Peltz's sale was disclosed in filings with the Securities and Exchange Commission, which do not say when the shares were sold or why.

So what motivated Peltz's decision? It's hard to point to an obvious impetus, as Starbucks' stock has continued on its downward trajectory through 2008 (shares have lost almost half their value in the past year).

But an aggressive campaign of store closings, slowed expansion, and management restructuring announced in July were largely welcomed as a step in the right direction.

Whatever Peltz's reasoning, Schultz will be glad for the extra bit of breathing room as he attempts to right the ship.