Taylor Swift is more successful than Paul McCartney -- at least when it comes to second-hand sales of summer concert tickets.

TicketsNow.com, a resale ticket vendor, reports that Swift's Speak Now Tour was the top-selling music event on its site last month, accounting for 6.3% of all concert ticket sales, ahead of the 5.7% for McCartney's stadium tour. Swift played a lot more shows in July than the former Beatle did, so it could be argued that Sir Paul's shows were actually more in demand.

In any case, the news proves how powerful the 21-year-old pop-country star has become in the live music world. Swift has been delighting fans across the country with sold-out shows that include her biggest hits and unexpected cover songs. Her Speak Now Tour continues through the fall, wrapping up with two shows in New York City in late November.

Because TicketsNow is a ticket resale site, its sales figures are likely to be skewed towards higher-priced events that are already sold out and may not be truly reflective of the full scope of consumer ticket-buying activity. In third place on its list of concert ticket sales for July were U2, followed by Katy Perry and Lil Wayne.