As it rounded the final bend the horse was clearly under pressure and dropped back through the field sharply.
He finished 25 lengths behind the second-last horse.
Chief steward Terry Baily said the seven-year-old collapsed and died when he returned to the tie-up stalls after the race.
Racing Victoria vets will conduct an autopsy.
"It's a shame. We had such a nice, clean-run Melbourne Cup," Bailey said.