According to reports from Bloomberg, Ackman was positive on the company's repurchase plan which he said was "aggressive." He was also positive on the new CEO George Jones, a former Saks executive.
Ackman recently told Barron's that he increased his stake in Borders' rival Barnes & Noble (BKS) from 2.3% to 8%. Ackman made similar comments on Barnes & Noble, saying the stock is significantly undervalued.
Ackman may be best known for his fight to implement changes at McDonald's Corp. (MCD). He was also instrumental in getting Wendy's International (WEN) to make aggressive changes, including spinning off its Tim Horton's (THI) chain.
Shares of Borders Group are up about 10% to $23.71 in early action Thursday.
Related: Media coverage: Bloomberg • TheStreet.com • Commentary: Excerpt from the mentioned Barron's feature • Borders Wobbles: Could It Be Ripe for a Takeover Bid? • Borders Needs a Savior

