Once, returning from an extended trip to France to settle his grandfather's estate, Benoist's ship was wrecked in the Bay of Biscay, north of Spain, an area noted for its storms.
After his return home, Benoist developed an interest in financial affairs and he abandoned his legal practice in favor of brokerage and real estate.
Both the parent house and the New Orleans branch were regarded as leading financial institutions of the Southwest and did a large business until 1842.
The Encyclopedic History of St. Louis wrote of him: "It may truly be said of him that he was not only one of the great Western financiers of his day and generation, but was a remarkably progressive man in every respect.
During the financial panic of 1857, when banking-houses were failing all over the United States, his bank weathered the storm, its resources unquestioned, his honor and fidelity to the trust reposed in him being regarded by the public as a guarantee of the stability of the institution of which he was the head."