London Olympic organizers announced Wednesday that 1.8 million people have made more than 20 million ticket requests for the 2012 Games.
Some 6.6 million tickets were made available online during a six-week sale until Wednesday morning.
Both the opening and closing ceremonies have sold out, with the opening on July 27, 2012, at the Olympic Stadium 10 times oversubscribed, organizing committee chairman Sebastian Coe said.
The first sold-out sports are track cycling, rhythmic gymnastics, triathlon, modern pentathlon and the cross-country equestrian competition. Most of the swimming and tennis sessions have sold out.
Tickets will be allocated through a ballot, or lottery, system. Tickets for track and field sessions in the main 80,000-seat stadium are still available.
While organizers said tickets for more than half of the 650 sessions across 26 sports were oversubscribed, they did not disclose how many of the 6.6 million tickets remain unsold.
There will be more sales in June and July.
"We are thrilled with the response right across the board, in all sports and all sessions," Coe said. "There will understandably be disappointment and we will find a way to go back to those people with other tickets.
"What is most encouraging is that the majority of applications are for multiple tickets and for several sports, which shows that friends and family are planning to go to the games together."
Organizers said 95 percent of the applications from the U.K. The online sales also were available in 26 European countries. Elsewhere, tickets are sold through national Olympic committees.
Prices ranged from $33 for some events to $3,320 for a top seat at the opening ceremony.
Applications will be processed in May and June, with customers notified by June 24 if they have been successful.
LOCOG has budgeted about $825 million from ticket sales, about a quarter of its overall operating budget.