Blanket Olympic television coverage and cancelled horse races in a soggy summer reduced the sums gambled in British betting shops, bookmaker Ladbrokes said
The Olympics in London were popular with people in the UK, but this did not translate into a surge in business for bookmakers.
Many of the sports in the Games do not attract large numbers of gamblers.
Ladbrokes, Britain's second-largest bookmaker, said amounts staked in its British betting shops fell 4.9% in the three months to September.
This period covered the Olympics and Paralympics, while bad weather caused the cancellation of 38 horse racing meetings.
"You had 24 hours of free, high-quality TV sports and it went on for four or five weeks. People were watching that rather than going to betting shops," said Ladbrokes chief executive Richard Glynn. "It's a once in a lifetime thing," he added.
Ladbrokes has about 200 shops in Ireland.
Online gambling exchange Betfair Group said last month Olympics mania had sapped interest in betting on soccer and horse racing in August.
Ladbrokes said that that its quarterly operating profit reached £49.2m sterling, barely changed from £49m a year earlier. Net revenue rose 3.9%.
"Though the economic outlook remains uncertain, we remain confident in our delivery and are in line with the board's expectations for 2012," Glynn said.
Ladbrokes said first versions of its new online sports betting website had been successfully released and it planned to migrate customers on to the platform by the end of the fist quarter of next year.
The company's first-half performance had been hit by problems in its digital business - comprising online, tablet and mobile - where profits halved, in contrast to rivals who have seen strong growth online. It has been investing more than £50m on technology over the past two years and expects to start to see a payback from 2013.
Glynn said Ladbrokes would look at acquisitions only if the price were right and they did not embroil the company in regulatory problems.
Takeover talks with online gaming company Sportingbet foundered last year over regulatory concerns related to business in Turkey. William Hill has now joined forces with GVC Holdings for a £530m takeover of Sportingbet, which won provisional approval this week from the Sportingbet board.
