Chesapeake Energy Corp.'s stock rebounded Thursday, closing up 45 cents, or 2.7 percent, to $17.19 a share.
Chesapeake's stock dropped to its lowest level in three years Wednesday after reporting lower-than-expected earnings and news that CEO Aubrey McClendon had operated a hedge fund inside the company.
On Thursday, Bernstein upgraded the stock from underperform to outperform, expecting the company's current issues to be resolved.
The stock closed Wednesday at $16.74 a share, down $2.86. The drop erased $1.8 billion from the company's value.