How Big is UltraSignup?

From the ‘Advertising tab’ on UltraSignupNews:

We boast a dedicated base of over 5M annual visitors, 650K active emails, and 6,000 races.

And more:

Our 5M annual runners make up 45% of total U.S trail running participation.

This are some fantastic numbers for UltraSignup, and for us to digest and mull over.

For example: the UTMB World Series has 41 events globally. So if we guesstimate an average of 4 races per event and an average of 1,500 runners per event we’re looking at 164 events and 246,000 race entries globally. In North America UTMB owns six events (not counting Western States), 17 race distances with I am guessing an average of 400 runners each? So UTMB is offering 6,800 race entries in North America.

If we consider 6,000 races on UltraSignup (predominately in the US) and guesstimate an average of 200 race entries we’re looking at 1,200,000 race entries available on UltraSignup.

So, UTMB is offering as many RACE ENTRIES in North America as UltraSignup lists RACES. But, tell me again how UTMB is a monopoly?