A "perfect storm of football results" this weekend meant betting company Coral lost £400,000 across its branches in Northern Lincolnshire.
The company, which has eight betting shops across Grimsby, Cleethorpes and Immingham, has estimated national losses were around £6 million.
Coral spokesman Simon Clare said: "It was a perfect storm of football results.
"Saturday was total carnage for bookmakers with nearly all the most popular selections on our coupons winning. Many of our betting shops were sending out for more money to pay hordes of winning punters and the damage was just as bad for our online division.
"This was another golden day for thousands of football punters many of whom have turned just a few quid into thousands of pounds and left Coral facing a mulit-million-pound bill. Coral had over 150 customers who won more than £2,000 for stakes of less than £30,
"The only saving grace was Arsenal's victory over Manchester City which saved Coral more than a million pounds worth of extra pain.
"The upside is that these are all regular punters whose tales of success will be the best possible advert for the fun of betting."
