Chick-fil-A is growing at such a rapid pace that it is expected to become the third largest fast food chain in the U.S., surpassing competitors like Subway.

Business has been booming for Chick-fil-A, as sales for the chicken sandwich chain soared by 15.5 percent in 2018 and traffic to its stores went up by 10 percent since 2017.

But the privately-held chicken sandwich franchise is making such a splash that it is catching up to publicly-traded competitors such as McDonalds and Wendy’s years ahead of schedule.

Kalinowski Equity Research told Marketwatch that Chick-fil-A’s popularity is growing faster than expected, as the chain was not expected to grow this quickly until 2020.

“We have long pointed out that Chick-fil-A is the restaurant competition with which McDonald’s U.S. should most concern itself – and by extension, investors should too,” according to a statement from Kalinowski Equity Research. “But this goes beyond McDonald’s.”

The chain’s projected sales for 2018 are expected to top $10 billion, even though the chicken sandwich joint is only open six days a week to keep company founder Truett Cathy’s wish to close the stores on Sundays to observe it as a holy day.

McDonalds took the stop spot for America’s largest fast-food chain in 2017, reporting $37.6 billion in sales. Starbucks took second place, reporting sales of $17.65 billion.

Although the chain has been rejected on some college campuses for its traditional Christian values, it is expected to expand in states like Massachusetts, New Jersey, and Ohio to compete with larger fast food chains.

The fast-food chain has also made the news this year for its good deeds, such as opening on a Sunday to feed first responders and stranded airport passengers.