Halep and Eugenie Bouchard made their debuts at the event.
Williams became the third female player to win three consecutive WTA Tour Championships singles titles, and the first since Monica Seles in 1992. During the tournament, Williams sealed her second consecutive and fourth overall year-end World No. 1 Ranking. She became the first woman to hold the No. 1 ranking for the entire calendar year since Steffi Graf in 1996.
For the first time since 2004 and just the second time ever, a player with a 2-1 round robin record failed to reach the semifinals. This was Ana Ivanovic, who would have reached the semifinal had she defeated Halep in straight sets in her last round robin match.