NEW YORK — Private equity firm Sycamore Partners is buying office supplies chain Staples for $6.9 billion.

The companies said Wednesday that shareholders of Framingham, Massachusetts-based Staples will get $10.25 per share.

Staples’ stock closed Wednesday up 77 cents, or 8.4 percent, to $9.93, fueled by a late-afternoon report of a deal. The stock rose another 1.5 percent in extended trading after the deal was announced.

Changing shopping patterns, like the shift to online buying, have hurt office-supplies megastores like Staples. Amazon has become a prime competitor to Staples for corporate customers.

Austin’s Staples closed a few years ago.