Wesley Barbossa So (born October 9, 1993) is a Filipino-American chess grandmaster, a three-time U.S. Chess Champion, and the first World Fischer Random Chess Champion. He is also a three-time Philippine Chess Champion. On the March 2017 FIDE rating list, he was ranked number two in the world and had an Elo rating of 2822, making him the fifth-highest-rated player in history.
In 2019, So said his favorite form of chess is chess960 (also known as Fischer random chess). Later that year, So became the inaugural World Fischer Random Chess Champion after defeating Magnus Carlsen to win the FIDE World Fischer Random Chess Championship.
A former chess prodigy, So became the youngest player to pass a 2600 Elo rating in October 2008, breaking the record previously held by Carlsen. This record has since been broken by Wei Yi, John M. Burke and Yağız Kaan Erdoğmuş. In early 2013, So passed 2700 and in January 2017 he became the 11th player to pass 2800 Elo.
So represented the Philippines until transferring to the United States in 2014. He won the 2015 Bilbao Chess Masters, the 2016 Grand Chess Tour title after claiming victory in the Sinquefield Cup and London Chess Classic, the 2017 Tata Steel Masters, the 2021 Grand Chess Tour, and the 2025 Sinquefeld Cup. He represented the US on board 3 at the 42nd Chess Olympiad, winning team and individual gold.
So was born in the Philippines in 1993 to Filipino-Chinese William and Eleanor So. He has one older sister, Wendelle Barbossa So, and one younger sister, Wilma Barbossa So. So attended the Jesus Good Shepherd School and Saint Francis of Assisi College in Bacoor.
Representing the Philippines (2003–2014)
So was at the age of ten years old when he began competing in junior tournaments. So took first place at the 2003 Philippine National Chess Championships in the U-10s section. As a junior player, he also competed in various sections of World Youth Chess Championships, finishing 19th in the U-10s in 2003, 13th in the U-12s in 2004 and fourth place in the U-12s in 2005. He also took part in the ASEAN Open U-10s in 2004, securing individual golds in the standard and rapid sections along with team silver medals in the standard and rapid along with winning individual golds in the standard, rapid and blitz sections in the U-12s in 2005.
So made his tournament debut at the Nice International Open in August 2005, finishing in sixteenth place (from 159) with 4/7. He also completed three International Master norms in the space of four months, becoming the youngest Filipino to achieve that status after scoring 5/9 at the Dubai Open, 5½/9 at the San Marino Open and 6½/11 at the Dato Arthur Tan Malaysia Open. During this period, So made his first Olympiad appearance on second reserve board at the 37th Chess Olympiad held in Turin in 2006.
So's form continued with 5½/9 at the Calvia Open, his first GM-norm with 7/9 at the Bad Wiessee Open, tying for sixth with 4/8 at the GMA Presidents Cup in Parañaque and ended 2006 by scoring 6/9 at the Singapore Masters. In January 2007, So qualified for the Chess World Cup 2007 via the Zonal tournament held in Phú Quốc, Vietnam, scoring 5½/9. Between January 2006 and April 2007, So had increased his FIDE rating by 303 points to 2519.
In May 2007, he went on to become Philippine National Junior Chess Champion. So got his second GM norm by scoring 7½/13 at the 2007 World Junior Chess Championship in Yerevan. He achieved his third and final Grandmaster norm on December 8, 2007, at the Pichay Cup International Open (Manila, Philippines), thus becoming the youngest Filipino grandmaster at the age of 14 and the seventh youngest to reach the title.
January 2008 saw So finish fourth with 7/11 at the ASEAN Chess Circuit event held in Tarakan, Indonesia. In April 2008, So shared first place at the Dubai Open, scoring 7/9. He also finished in third place with 7/9 at a blitz tournament held during the rest day. So then defeated Susanto Megaranto 4–2 in a six-game match as part of the JAPFA Chess Festival held in Jakarta, won the "Battle of Grandmasters tournament" with 8½/11 (+6−0=5) in Manila, came tenth with 7½/11 in the Philippines Open followed immediately with second place at the Subic Open with 6½/9.
In July 2008, So came second with 12½/17 in a tournament to decide the team for the 2008 38th Chess Olympiad, followed by sharing eighth place at the World Juniors Championship held in Gaziantep, Turkey. He shared second with Zurab Azmaiparashvili scoring 6½/9 at the Vietnam Open but finished well back at the Arroyo Cup in sixteenth place. During the previous 3-month rating period So completed 69 rated games.
After competing in the Asian Club Cup, So made his first appearance at a major chess tournament by winning the Corus Group C in January 2009, a point ahead of Anish Giri and Tiger Hillarp Persson with a score of 9½/13, earning a spot in Group B the next year. He scored 5/9 and shared 17th place at the strong Aeroflot Open held in Moscow. He showed his strength against home opposition scoring 9/11 at the Dapitan City Battle of GMs, but found it difficult at the Asian Continental Championships in Subic, scoring 6½/11 and sharing 18th place. So won a seat in the 2009 Chess World Cup by finishing second at the Zonal Championship held in July 2009 in Ho Chi Minh City, Vietnam. After competing in the Chinese Chess League, So shared fourth place at the SPICE Cup Group A with a solid 4½/10.
At the age of 16, So became one of the stories of the 2009 Chess World Cup held in Khanty-Mansiysk after progressing to the fourth round before being knocked out by Vladimir Malakhov after rapid tiebreaks. He defeated Gadir Guseinov after rapid tiebreaks then defeated Vassily Ivanchuk and Gata Kamsky. This was followed by sharing fourth place at the Corus Chess Group B in early 2010 with Erwin l'Ami scoring 7½/13 and sharing seventh place with 5½/9 at the Aeroflot Open. Sharing second place with 6½/9 at the Asian Continental Championships in April earned him a spot in the Chess World Cup 2011 and he secured a second Philippine Chess Championship.
As So's playing strength and rating increased, so did the number of invites to high-level events. So initially led the strong Biel tournament before drifting back to share fifth place with 4½/9. Three weeks later, So held his own in the last NH "Experience vs Rising Stars" Match (played under Scheveningen match rules) scoring 4½/10 for the "Rising Stars" team. So took part in the 39th Chess Olympiad and placed fourth, scoring 5½/10 at the 2010 SPICE Cup, before the Asian Games.
So tied for fourth place at Tata Steel (formerly Corus) Group B but withdrew from the Aeroflot Open, held soon after, citing exhaustion from the previous event. In July 2011 he won the Philippine Chess Championship for a third time. So's rating hovered over the coming year with a solid performance at the strong AAI International Tournament in New Delhi among performances typical for his rating.
In 2012, So got a scholarship offer from Webster University, which was his affiliation for two-and-a-half years before becoming a full-time professional. In August 2012, So emigrated to the United States. In September 2012, So found success in first place at the Quebec International, scoring 7½/9, half a point ahead of Lazaro Bruzon and at the 40th Chess Olympiad drew against numerous top-level players including Levon Aronian, who described So as a "talented player from a country with a great chess culture".
So came second in the Zonal 3.3 Championship in Tagaytay, Philippines earning a place in the Chess World Cup 2013 and shared first place with Pavel Eljanov and Bassem Amin at the Reykjavik Open. In doing so he breached the 2700 Elo mark, considered to be the level of an elite player and placed him 50th in the World. So also won gold at the 2013 Summer Universiade in Kazan, Russia, the first such medal for the Philippines, after a play off match with Zaven Andriasian. After defeating Alexander Ipatov in the first round of the Chess World Cup, he was knocked out by eventual semi-finalist Evgeny Tomashevsky. In October 2013, So won the Unive Crown Group scoring 4½/6.