Rags for Britches (5), the 6-5 favorite, won Thursday's fourth race at Gulfstream Park West/Calder, to start the Rainbow 6.
The carryover coming in was $8.987, built up over one race day.
Bettors added $42,743 to the Rainbow 6, a 0 cent per combination-only bet.
The race was one mile on the Sloppy dirt track, a $6,250 claiming race for 3-YO and up.
Rags for Britches rallied from fourth place in mid stretch and beat Ninetydaysofwinter by four lengths.
Marcos Meneses rode the winner for trainer Carlos Perez.