McDonald's is selling a 50-piece box of chicken for $9.99. Burger King's deal is a 10-piece for $1.49.

There's an important reason the fast food giants are selling chicken for half-price, writes Craig Giammona at Bloomberg Businessweek.

"With wholesale beef prices near a record — up 40% since 2012 — McDonald's and Burger King are hoping cheaper nuggets will help boost sales to price-sensitive diners," he writes.

Droughts have caused a worldwide beef shortage.

Traditional fast food chains have been losing millennial consumers to fast-casual chains like Chipotle and Five Guys.

Because their food isn't seen as high-quality, the fast food companies have to focus on low prices to attract diners.

But with beef prices at near all-time highs, operators can't afford to discount Whoppers or Big Macs.

Burger King isn't stopping at chicken nuggets.

The brand has recently brought back its discontinued Chicken Fries and ham-and-cheese Yumbo.

Burger King's promotional strategy has helped the company boost sales during an industry-wide slump.

To help offset the discounts, Burger King raised the prices of some items.