Microsoft billionaire Paul Allen reportedly just bought another home for $5.4 million

Microsoft co-founder Paul Allen is no stranger to the Mercer Island, Washington, real estate market.

Allen, whose net worth is estimated at $18 billion, is believed to own as many as 11 homes in this ritzy enclave just east of Seattle.

And according to Realtor.com, he just added yet another Mercer Island property to his extensive collection.

Allen reportedly purchased a roughly 3,320-square-foot home for $5.4 million in December. The property is a bungalow that dates back to 1948 and has four bedrooms and four bathrooms.

Allen's primary residence is a 10,000-square-foot waterfront home that has its own helipad and concert hall. The rest of his Mercer Island homes are used to house guests, including one that's reserved just for his mother.

Allen also owns property in Beverly Hills, Hawaii, New York City, and the French Riviera, in addition to two superyachts.