Hedge fund Jana Partners LLC disclosed in a regulatory filing on Tuesday that it had acquired a 6.2 percent stake in grocery chain Inc SWY.N.
Jana said it has held talks with Safeway management about reviewing strategic alternatives for the Pleasanton, California-based company and that its shares are undervalued.
The hedge fund also said it has spoken with Safeway about exiting lower margin geographies.
Safeway said on Tuesday it had adopted a so-called poison pill to prevent an unwanted takeover of the company.
Safeway is working with investment bank Goldman Sachs Group Inc (GS.N) to defend the company against a takeover, according to a source. Goldman Sachs declined to comment.
Safeway sold its Canadian assets to Empire Co Ltd (EMPa.TO), the parent of Canada's second-largest grocery chain, in June for $5.7 billion.
It also spun off its gift card unit Blackhawk Network Holdings Inc (HAWK.O) earlier this year.
Safeway operates its namesake chain as well as the Vons and Dominick's stores.
(Reporting by Olivia Oran in New York)