Target shares slid 2 percent to hit a 52-week low on Tuesday, after news of a downgrade and significantly lowered price target from Cowen.
Analyst Faye Landes lowered her price target for the retailer to $47 from $66, saying she expects the company to indefinitely suspend its buyback, which she called a "key support for the stock."
(Read more: 2 accused of using stolen Target account information)
Target shares are currently trading around $59. (Click here to get the latest quote.)
Landes' downgrade does not yet incorporate the numerous costs the retailer will incur in the wake of the massive data breach that ensnared as many as 110 million shoppers, including the potential need to upgrade some 50,000 point-of-sale systems, replace 40 million cards and ongoing legal fees.
(Read more: Breaches an 'Air Force One emergency': Saks exec)
"We don't know how much money we're talking about, but it's a lot," Landes wrote.
The retailer's shares are down 6.6 percent year-to-date.
(Read more: 2 accused of using stolen Target account info)
Target earlier this month revised its fourth-quarter earnings forecast, saying it expects earnings per share of $1.20 to $1.30, compared with prior guidance of $1.50 to $1.60. This factors in a comparable-store sales decline of about 2.5 percent, down from its prior forecast of flat same-store sales.
According to Thomson Reuters estimates, fourth-quarter earnings estimates have changed to $0.81 from $1.25 on the day the breach was initially reported.
—By CNBC's Krystina Gustafson. Follow her on Twitter @KrystinaGustafs.