Sept. 3 (Bloomberg) -- Until recently, sports betting had one major flaw -- you had to make sure your bet was placed before the event started. If you got caught in a traffic jam or forgot what time a game began, you couldn't play.

Bookmakers have realized there's a demand for betting ``in running,'' or placing a wager any time from kickoff until the final whistle of a televised sports event. At most major online betting companies you can now bet from the moment a televised match starts until the result is known.

In-running betting was pioneered during the early 1990s in Europe on golf tournaments and soccer matches. It's now widely accepted on NFL, MLB, NBA and NHL games. There was even in- running betting on some Olympics events, or at least the ones that lasted more than few seconds (betting on the men's 100 meters in running would have been tricky). Soccer, golf, tennis and cricket are the dominant sports in terms of betting volume, mainly because there are so many matches.

For the bookies, in-running betting has become their biggest growth area. Five years ago it was considered a niche product, offered only by one or two bookies looking to differentiate themselves. Bookmakers now say in-running betting accounts for up to 30 percent of their revenue and that it is growing rapidly. Several predict it will account for half their business by 2010.

Golf Tournament

Peter Fisher, founder of Gibraltar-based online bookmaker Stan James, widely considered the pioneers of online sports betting, started offering in-running markets in 1994. ``I remember going home and watching the end of a golf tournament,'' he says. ``It was a play-off between Nick Price, Scott Simpson and Hale Irwin, and I thought, `People must want to bet on this. They're watching TV and everyone will have an opinion on it. Why isn't anyone offering odds?'''

``So, the next week we started betting on the final round of that week's tournament and we lost a fortune! But the business took off and we've made our reputation on the idea that if it is on television, we'll bet on it in running,'' says Fisher.

Betting exchange Betfair, which allows bettors to bet against each other rather than against a bookmaker, has created a new type of bettor who trades in-running sports markets in the same way they would day-trade Wall Street. ``We had a lot of trading on the Federer vs. Nadal final at Wimbledon this year,'' says Betfair spokesman Robin Marks. ``Only $12.4 million was bet on the match before it started, but $82.4 million was traded in running.''

Delayed Broadcasts

In running has brought its own issues for bookmakers, mainly because the televised feeds that they receive in their offices (and the ones you receive at home) are delayed from the live match. It is normally only about three seconds but, in some cases, it can be 10 seconds or longer.

This means that bettors can sit at racecourses, football grounds or even the Olympics with a laptop computer and a wireless connection and get bets on the match before the bookmaker sees it on TV. Most bookies now have a small delay in their bet acceptance procedures to help guard against this, but if the delay is big enough they will find themselves taking bets after something crucial has happened.

British police are currently investigating the deaths of a Chinese man and his girlfriend who allegedly employed spotters at British soccer matches to beat in running bookmakers in China and Southeast Asia, according to news reports. They are said to be investigating reports that Zhen Xing Yang had been murdered by either bookmakers upset at his scheme or by some of the spotters, who it is claimed he failed to pay for their work.

Contrarian Bets

In terms of the best strategy for winning at in-running betting, bookmakers say most bettors tend to follow the momentum in a game and bet as though that will continue; if a team scores a touchdown, in-running bettors will pile their bets on that team.

If Tiger Woods sinks an 18-foot putt, then bettors will take any price about him winning the tournament. Sharp in- running bettors are generally contrarians and will bet against the general public, on the basis that in sport momentum can change very quickly. I've found it to be a profitable strategy - - you don't win all the time but when you do, you win big.

(Joe Saumarez-Smith is chief executive officer of Sports Gaming, a U.K. management consulting firm to the gaming industry. He also owns European online bingo companies and odds comparison Web sites. The opinions expressed are his own.)

To contact the writer of this column: Joe Saumarez-Smith at jssmith15@bloomberg.net

Last Updated: September 3, 2008 00:01 EDT