The ski-jumping son of a top Cantor Fitzgerald exec crash-landed on a Long Island woman at a Utah resort, seriously injuring her, a lawsuit claims.

Alexis Siegel, 42, says she was slowly making her way along the Hawkeye Trail at the famed Deer Valley Ski Resort last month when teenager William Lehrman — whose dad, Michael, runs Cantor Fitzgerald Commercial Real Estate — “violently collided” with her.

William flew 25 feet on “an improper and unsafe jump,” she claims.

The crash left Siegel with nerve and tendon damage so bad, she hasn’t had use of her right arm since the March 21 incident, said her lawyer, Joel Robinson.

The Lehrmans declined to comment.