LAS VEGAS -- Ultimate Fighting Championship hits a huge milestone this weekend when they present their 100th fight card. But this Las Vegas-based company does more than just entertain. UFC is a huge cash cow for the city.

Mandalay Bay is sold out this weekend, and the Strip will be buzzing for the summer's biggest event in Las Vegas.

UFC brings in an estimated $400 million a year to the local economy, making these fights a "fistful of dollars."

The UFC is one of the fastest growing spectator sports in the world.

“It's a huge event, as far as the fights are great, people love it, and everybody leaves buzzing after UFC 100,” said UFC President Dana White.

White said Saturday night's card will have over a million Pay-Per-View buys. It will be seen live in 51 countries, tape delayed in 24 others, broadcast in 17 languages and will be shown in China and Mexico for the first time.

That's not only an estimated 300 million homes watching the fight -- it's an unpaid world-wide tourism ad for Las Vegas.

“We're very overlooked by the Las Vegas community,” White said. “We bring $400 million a year into the city of Las Vegas, so hopefully, people will wake up. But I know people who do love UFC. In this town, we're the home team.”

One group that doesn't overlook UFC's significance is the hospitality industry. Mandalay Bay officials said they are giddy with the added traffic they'll get this weekend.

“Especially at a time where we're, clearly from the economy, struggling a bit, we're looking for reasons to bring people here, give them excitement and show off the town as we do so well. So, yeah, it's got a huge economic impact for this city,” said vice president of marketing Scott Voeller.

These are called appointment events, which could lead to follow-up trips -- all bonus dollars -- making UFC stand for Ultimately Facilitating Cash.

The event in the arena is sold out, but it can be bought on Pay-Per-View, and most casinos in the Valley are holding parties to watch the closed-circuit broadcast.

There is also a fan expo at Mandalay Bay Convention Center Friday and Saturday. It's the first time this will be held, and as many as 50,000 people are expected to check it out. FOX5 will have more on the fan expo Friday morning on Live in Las Vegas, and will be live at the fight at 10 p.m. Saturday.