Amazon.com Chief Executive Officer Jeff Bezos is daring rival retailers to raise their minimum wage to $16 an hour.

Bezos laid down the challenge in his annual shareholder letter, published Thursday. Bezos routinely uses the letter to outline his long-term strategy, which made him the world’s wealthiest man and Amazon one of the most valuable companies.

“Today I challenge our top retail competitors (you know who you are!) to match our employee benefits and our $15 minimum wage,” Bezos said. “Do it! Better yet, go to $16 and throw the gauntlet back at us. It’s a kind of competition that will benefit everyone.”

The company in October pledged to pay all of its warehouse workers at least $15 an hour, after presidential hopefuls Bernie Sanders and Elizabeth Warren held out Amazon workers on food stamps as an example of the need for living wage protections.

Bezos includes his 1997 shareholder letter to remind investors of his ability to capitalize on how the internet would change the nature of shopping. His strategy and outlook have developed a cult-like following similar to that of Warren Buffett, whose annual letters to Berkshire Hathaway Inc. investors are must-reads for those looking to understand the economy and Buffett’s investment strategy.