Corbis Entertainment is a division of Corbis, a digital content and entertainment rights company founded by Gates in 1989.
The US-based firm, which is thought to have annual revenues of around $50m (£29.7m) a year, provides music licensing, public relations and celebrity partnerships for clients such as Heineken, General Motors and Dunkin donuts.
“We work with local brands, helping them to connect to consumers through entertainment. WSM is a mirror of our firm but with sport,” Mark Owens, executive vice president of Corbis Entertainment, told City A.M.
“We have a very strong presence in North America and WSM will give us a big anchor in Europe now.”
WSM, which posts revenues of around $10m a year, worked with Corbis on a couple of projects prior to today’s acquisition after a mutual contact introduced the two companies.
WSM’s clients include investment firms Aberdeen Asset Management and Threadneedle.
“The deal is a good strategic fit and will help us grow in the US,” said Andrew White, chief executive and founder of WSM.
The terms of the deal were not disclosed. Corbis Entertainment has made a number of acquisitions over the past two years, including entertainment marketing firm Norm Marshall & Associates.
Owens said the firm will “continue to look for strategic partners”.