More than 400,000 people submitted a combined 8.1m transactions during the first weekend of Massachusetts online sports betting.

The data comes from the geo-tracking company GeoComply, which provides gambling analytics and insights to different entities. The results of opening weekend are highly promising for a New England area that has a growing presence in the country’s gambling ecosystem.

the online arm will add $60m in annual tax revenue

Online sports betting launched in Massachusetts on March 10, pairing with the retail market that started on January 31. Officials estimate that the online arm will add $60m in annual tax revenue to the state kitty.

Of the 8.1m transactions, roughly 5,000 were blocked by GeoComply due to suspicious origin or accounts.

“With the gold standard of geolocation in place and an experienced team of experts, we are uniquely positioned to lead the fight against fraud in all its forms,” said Lindsay Slader, GeoComply’s senior vice president of compliance.

Nearly all of Massachusetts’ neighboring states, including New Hampshire, Connecticut, Rhode Island, and New York, have legal sports betting markets.

Massachusetts also churned out the fifth-most online bets this past weekend, behind only New York, New Jersey, Ohio (which also launched its online sports betting market this year), and Pennsylvania. Participation is also likely to grow in the immediate future thanks to March Madness tipping off Tuesday afternoon and running through April 3.