Another investor piles onto Hertz

Now that Hertz consented to Carl Icahn's demands for new management and seats on the board, the car-rental giant is facing yet another activist shareholder.

First reported by the New York Times DealBook on Oct. 20, Jana Partners raised its stake in Hertz to 7%, now making it the company's second-largest shareholder behind Icahn. In total, Jana has invested $579 million in Hertz, which relocated its headquarters to Southwest Florida from New Jersey last year.

Jana, led by activist investor Barry Rosenstein, targets companies like Hertz that are struggling and ripe for change. The fund manages about $11 billion in investments, and Rosenstein often takes an active role in the companies in which he invests.

Indeed, in a filing disclosing the acquisition of additional shares (the fund reported a 1.3% stake in June), New York City-based Jana says it considers Hertz shares to be undervalued and may consider acquiring a larger stake in the company and pushing for additional changes in management and strategy, such as a merger.

Investors welcomed the news. Hertz's stock (symbol: HTZ) rose 6% on the day Jana disclosed its increased stake.