PetSmart Inc (PETM) plans to explore a potential sale of the company, people familiar with the matter said on Tuesday, after several shareholders led by activist investor Jana Partners LLC pressured the pet supply retailer to sell itself.

PetSmart, which has a market capitalization of nearly $7 billion, could announce the intention to explore strategic alternatives as soon as this week, although the timing could yet change, one person said.

There is no guarantee the review will lead to a deal and PetSmart could still determine that it would be better off on its own, the people cautioned, asking not to be named because the matter is not public.

Representatives for PetSmart could not be immediately reached for comment.

Shares of PetSmart rose 3.4 percent to $70.80 in late afternoon trading on the news.

PetSmart's likely move marks yet another victory for Jana. The firm, which is run by Barry Rosenstein, has amassed stakes in companies it perceived to be undervalued and successfully pushed them to sell themselves in recent months.

Earlier this year, Jana pressured engineering and construction services firm URS Corp to pursue a sale, resulting in its takeover by industry rival AECOM Technology Corp for $4 billion.

Last year, Jana pushed Safeway Inc to review strategic alternatives after disclosing a stake in the grocery chain in September. Safeway agreed in March to be acquired by private equity firm Cerberus Capital Management LP in a deal valued at about $9.4 billion.

PetSmart has faced mounting investor pressure at a time when fierce competition from large retailers including Wal-Mart Stores Inc and Amazon is squeezing specialty stores.

Jana Partners, which has reported a 9.8 percent stake in PetSmart, has been calling on the company to pursue a sale after what it calls years of financial underperformance. It has been joined in its push by other investors, including Longview Asset Management.

Phoenix-based PetSmart, founded in 1986, has about 53,000 employees and operates more than 1,340 pet stores, according to its website. 

(Reporting by Soyoung Kim in New York; Editing by Leslie Adler)