The 28th International 500-Mile Sweepstakes Race was held at the Indianapolis Motor Speedway on May 30, 1940. The winner was Wilbur Shaw in the same Maserati 8CTF he had driven to victory in 1939. Shaw became the first driver in the history of the race to win in consecutive years. It also marked Shaw's third win in four years, making him the second three-time winner of the race. Shaw's average speed was 114.277 mph, slowed by rain which caused the last 50 laps to be run under caution. Shaw took home $31,875 (equivalent to $732,519 in 2025) in prize winnings, plus additional prizes that included a car and a refrigerator.

The first three finishers – Shaw, Rex Mays, and Mauri Rose – were allowed to finish the race. Fourth place finisher Ted Horn, however, was flagged due to the rain shower. Though it appears he may have actually completed all 200 laps, officials ceased scoring Horn (as well as all other cars) immediately after third place Rose crossed the finish line. Horn was officially credited with completing 199 laps – one lap short of the full distance. This marked the only blemish on his noteworthy record of nine consecutive races completing every lap. He eventually completed 1,799 out of a possible 1,800 laps from 1936 to 1948.

The top four starting positions finished in the top four places, albeit in shuffled order.

Note: Relief drivers in parentheses

 W  Former Indianapolis 500 winner

 R  Indianapolis 500 Rookie

All entrants utilized Firestone tires.