Lockheed Martin stock dropped about $12 in the blink of an eye on Wednesday.

Midday, the defense contractor’s shares sunk to $447.20 from $459.40. Management comments at a BofA Securities investor conference looked like the best reason.

Lockheed CFO Evan Scott presented and said there could be delays for the F-35 production lot 18 award from the U.S. Defense Department. The F-35 is the company’s advanced fighter jet—the Pentagon awarded a Lot 18 contract in December worth $11.8 billion for 145 jets.

Scott said Wednesday that lots 18 and 19 could be combined into a single award.

“On the plus side, that accelerates…roughly 150 jets of backlog potentially into the second quarter. However, the overall award now is probably going to happen later in the second quarter than if Lot 18 had been a standalone,” he said.

That delay could pressure second-quarter estimates, something investors might not like. What’s more, the company is seeing cost pressures in some of its classified programs.

Lockheed stock came off its lows for the day, but still ended the session 2.3% lower at $449.18. In comparison, the S&P 500 was flat, and the Dow Jones Industrial Average lost 0.2%.

As Wednesday, Lockheed had fallen about 18% since the Nov. 5 presidential election. Criticism from Trump advisor and Tesla CEO Elon Musk about the F-35 has weighed on investor sentiment. The F-35 accounts for roughly one-quarter of Lockheed’s total revenue.