Auction of private meal with Warren Buffett held in late May

Investor Warren Buffett has already raised nearly $30 million for a California homeless charity over the years, and he's getting ready to auction off another private lunch.

The auction planned for late next month will be the 20th time Buffett has raised money for the Glide Foundation, which helps the homeless in San Francisco.

Since 2010, the auction has only finished below $2 million once.

Buffett's first wife, Susie introduced him to Glide after she volunteered there. She died in 2004, but the connection endured.

Buffett says he supports Glide because they help people in difficult situations find hope again in life.

The bidding starts at $25,000 on May 26 and runs all week. The winner can invite up to seven friends.