Air travel into and out of the U.K. may be supressed for a few years, according to Ryanair Holdings plc. Image source: Getty Images.

What: Shares of airline Ryanair Holdings plc (NASDAQ:RYAAY) plunged as much as 14.8% in morning trading on Wall Street Monday on more Brexit fallout. At 12:40 p.m. EDT shares were down 13.9%.

So what: Ryanair's management said that bookings have remained strong despite last week's Brexit vote. But fares are lower, which isn't helped by a plunging British pound, a headwind that could last for quite a while.  

The airline also said it would likely divert new aircraft to Europe, away from the U.K., given the uncertainty and weak currency. And investors don't like the potential economic and business upheaval Brexit will bring.

Now what: It's impossible to tell exactly what the impact of Brexit will be for Ryanair, but it doesn't appear to be positive. The weaker pound devalues the business on U.S. markets, and a floundering U.K. economy could be bad for demand as well. In the week before the Brexit vote, Ryanair CEO Michael O'Leary said there would be an economic downturn lasting two or three years if the vote passed, and the company's budget-conscious customers could be hit hardest.