A U.S. judge today rules against setting a price on Chrysler shares held by some of the auto makers’ retirees, possibly delaying Fiat’s full acquisition of the American car company and a planned initial-public offering.

Fiat has been attempting to purchase the stake from the Voluntary Employee Beneficiary Assn. since 2009, but there is dispute over the value of those shares. A call option allows for Fiat to make an offer, which must be approved by the court.

The VEBA holds 41.5% of Chrysler’s total shares. The ruling only affects some of that percentage, but it does slow Fiat’s full pursuit of the interest.

During a pair of conference calls this week, Fiat-Chrysler CEO Sergio Marchionne expressed confidence in a ruling in Fiat’s favor, which could have cleared the path to an IPO later this year. Now, Fiat must work through the court to come to an agreement to purchase the remaining shares.

Fiat says in a statement it “looks forward to resolving the few remaining issues in the litigation through the discovery requested by the court, and remains confident that those residual issues will also be resolved in its favor.”