Starboard Value LP is at it again. This time the activist hedge fund is training its sights on Yahoo, a stagnant Web portal now flush with $6 billion from the Alibaba shares sold in the IPO last week.

Since the firm was established in 2011, it has built up a track record of taking stakes in troubled companies, pushing for change and walking away with a healthy profit. One of its first targets was AOL, another legacy Web portal, which Starboard criticized in 2011-2012 for bad acquisitions (Huffington Post, Patch) and for not returning value to shareholders.

Two years later, in a somewhat ironic twist, Starboard managing partner Jeffrey C. Smith has changed his view: At the heart of his proposal for Yahoo is a merger with AOL  -- "a company we know well," he wrote. Smith lost his proxy vote to install three new members on AOL's board, but he walked away claiming victory. 

"We measure success by enhancing value for all shareholders, thereby producing returns for our investors. AOL adopted many of our suggestions, taking AOL stock from near an all-time low to near an all-time high," he said.

Yahoo is now feeling some of the same heat that Starboard applied to Darden Restaurants, which owns the Olive Garden and Longhorn Steakhouse chains. Starboard issued a nearly 300-page report earlier this month, laying out how Darden could make its operations more efficient and thereby increase earnings by $326 million.

The report made headlines for recommending that Olive Garden stop giving customers unlimited breadsticks, put salt in the pasta water and encourage servers try to sell customers more wine. The Glass Lewis advisory service said the plan is a good idea.

"Starboard has identified valid areas of concern, from a performance, operations and governance perspective, and outlined a realistic plan to improve the company's performance," Glass Lewis said, as quoted by Bloomberg Businessweek. Starboard "has nominated several director candidates who possess relevant experience and who are capable of overseeing a turnaround."

Before that, Starboard made waves when it bought a 13.3 percent stake in Office Depot in September 2013, saying the beleaguered office supply company's shares were "deeply undervalued" and recommending that the chain reduce its expenses.

The admiration was short-lived, though, and within a year, Starboard had removed three Office Deport directors from the corporation's board in favor of three Starboard choices. Any hurt feelings were almost certainly mended when Staples, Office Depot's primary competition, watched its share price slide 15 percent.  

Important Starboard Targets:

Darden Restaurants (2013)  

Emulex Technologies (2013)

Tessera Technologies (2013)

Office Depot (2013)

AOL (2011)