A 40-year-old Chicago investment honcho yesterday became the second person to die after competing in Sunday’s Nautica New York City Triathlon, officials said.

Amy Martich, a mother of three and a Janus Capital Group vice president from Elmhurst, Ill., went into cardiac arrest twice after the early-morning swim in the Hudson River, said triathlon director Bill Burke.

Transported in critical condition to Roosevelt Hospital, Martich succumbed yesterday.

Another race participant, Michael Kudryk, 64, of Freehold, NJ, died at the hospital after failing to complete the swim.