Both casinos have reported a double-digit decline in their October slot-machines revenues.

Mohegan Sun released figures Thursday showing it “won,” or kept, $42.6 million in slots revenue after paying out prizes last month, 10.6 percent less than the $47.6 million it kept in the same month last year.

Foxwoods announced earlier in the week that it kept $34.4 million in slots revenue after paying out prizes in October, down 10 percent compared with the $38.3 million it kept a year ago.

Also Thursday, the Massachusetts Gaming Commission released October revenue figures for MGM Springfield, the nearly $1 billion casino that opened in late August just north of the Connecticut border. In its second full month of operation, MGM Springfield kept $14.6 million in slots revenue, significantly less than the $18.1 million it kept in September.

September had five Sundays and five Saturdays, while October had four of each. Casinos typically do a big share of their business on weekends.

In response to questions about MGM Springfield’s effect, Foxwoods issued a statement.

“With MGM Springfield in its first few months of operation, not only did we expect to see an impact, we’ve also consistently and publicly communicated our expectations over the last three years while proactively working toward mitigating any potential loss in revenue,” said Adam Jalbert, a spokesman. “We are pleased to say that, despite the temporary decline in October, our business volume and gaming activity still continues to exceed our expectations.”

Mohegan Sun sent $10.8 million of its October slots revenue to the state while Foxwoods contributed $9 million.