2. US Open
US Open is a Grand Slam tennis tournaments that occurs LAST.
More information:
The US Open Tennis Championships is a hardcourt tennis tournament; founded in 1881. It has always been the fourth and final Grand Slam tournament of the year after the Australian Open, French Open and Wimbledon.
The prize money of US Open Tennis Championships (2021) was 57.5 Million USD. It was held in New York City, US and the venue was USTA Billie Jean King National Tennis Center.