The short answer is that it depends - on whether your agreement pertains to any one of the categories of things that must, as a matter of New York law, be reduced to writing, as set forth in General Obligations Law 5-701, also known as the Statute of Frauds. If not, it is quite possible that a New York court may find that a joint venture did, in fact, exist, and therefore, that a viable claim for, among other things, breach of fiduciary duty.