Yahoo has distributed letters to potential buyers to launch an auction for its portfolio of 3,000 patents that could earn more than $1 billion. The collection dates back to the company’s 1996 IPO, including its original search tech, say those familiar with the plans. “Yahoo has set a mid-June deadline for preliminary bids,” reports The Wall Street Journal, “and hired Black Stone IP, a boutique investment bank that specializes in patent sales, to run the auction.” Yahoo confirmed the sale of patents and pending applications “related to Web search and advertising.” The company is also selling its core Internet business; Verizon reportedly bid about $3 billion.