The opposite of a "closed deal" could be an "open negotiation." This would suggest that the parties involved have not yet come to a final agreement, and there is still room for discussion and compromise. Another antonym could be an "unfulfilled agreement," indicating that the deal was agreed upon but has not been completed. Alternatively, a "failed agreement" suggests that the parties were unable to reach an acceptable outcome, and the deal was ultimately abandoned. An "unfinished contract" could also be seen as an antonym since it implies that while progress has been made, the deal has not yet been finalized.