The ATP Tour 500 tournaments (previously known as the ATP World Tour 500 tournaments, ATP International Series Gold, and ATP Championship Series) are the fourth highest tier of annual men's tennis tournament after the four Grand Slam tournaments, ATP Finals, and the ATP Tour Masters 1000.
The series includes 13 tournaments, with 500 ranking points awarded for the events' singles champions – which accounts for the name of the series. Tournaments have various draws of 32 and 48 for singles and 16 and 24 for doubles. It is mandatory for leading players to enter at least four 500 events, including at least one after the US Open; if they play fewer than four, or fail to play in one after the US Open they get a "zero" score towards their world ranking for each one short. Roger Federer holds the record for most singles titles at 23, while Daniel Nestor holds the record for most doubles titles won with 20.
1990–1999 ATP Championship Series
2000–2008 ATP International Series Gold
2009–2018 ATP World Tour 500
2019–present ATP Tour 500
Bold face designates active players