Stroock & Stroock & Lavan, beset by partner exits in recent years, has been in merger talks with multiple Am Law 200 firms, but the law firm is facing some challenges to a combination, including its pension program for retired partners and its accrual accounting system, according to sources familiar with the matter.

In particular, Stroock has been in discussions with McGuireWoods, Steptoe & Johnson and, most recently, Squire Patton Boggs, according to a source. Representatives for these firms did not return messages seeking comment on merger talks.