Regal is the biggest, but also just the latest, exhibition chain to opt to use multiple online ticket sales services. And says that the deal means it has passed Comcast’s Fandango to become the No. 1 advance sales movie ticket company:  MovieTickets says it has 28,000 screens “worldwide” — although Fandango claims more than 25,000 screens in the U.S.

Regal will continue to use Fandango, and — by the end of this month — add MovieTickets at its 572 theaters with 7,356 screens. Regal’s closest rival, No. 2 AMC Entertainment, opted to use multiple online ticket sellers last year.  Carmike decided in 2013 to use MovieTickets and Fandango.

The pact “establishes as the leader in the advance movie ticketing category, based on both screen count and number of movie theater chains served,” says CEO Joel Cohen. It also “significantly boosts our footprint in the domestic marketplace and magnifies the opportunities for us on a much broader scale.”

MovieTickets  Co-Chairmen Shari Redstone and Mitchell Rubenstein say that, as co-founders of the service, “it’s especially meaningful to see us take a leadership position with such a significant addition.”

Online has become an important sales venue for most theaters. AMC reported last month that 14.3% of its Q4  ticket sales were made via the Web vs 10.3% at the end of 2013. “It is safe to expect continued progress in this area,” CEO Gerry Lopez told analysts.

The Regal chain includes Regal Cinemas, Edwards Theatres and United Artists Theatres.