The casino giant may pay up to $800 million to settle the suits, the group told the Securities and Exchange Commission in a quarterly report.
The company said it's "reasonably possible" an agreement will be reached by May 2020, MGM told the SEC.
MGM Resorts also said it has $751 million in insurance to pay toward a settlement. However, a lawyer handling mediation talks for plaintiffs called it premature for the corporate owner of Mandalay Bay resort to report a possible settlement range between $735 million and $800 million.
"We're not even close to resolving all the terms and issues before we have a settlement," attorney Robert Eglet said.
Eglet reportedly represents more than 4,000 claimants. That includes people who have sued outside of Nevada as well as those who have not even formally filed yet.
"It's true that a settlement is possible," Eglet said. "But I will tell you it's not probable. Nothing is signed. We have a long way to go before we have an agreement."
But MGM company spokeswoman Debra DeShong said progress has been made following multiple mediation sessions over several months.
The goal is "to resolve these matters so that all impacted can move forward in their healing process," she said.
The casino has previously fought back against liability claims connected to the mass shooting — the deadliest in modern U.S. history.
In July 2018, MGM Resorts International filed lawsuits against the more than 1,000 victims of the attack. In the suits, which only asked for claims against MGM-related parties to be dismissed, the casino argued that “plaintiffs have no liability of any kind to defendants.”
Plaintiffs are currently seeking compensation for a range of physical and psychological harm after a shooter rained gunfire from a Mandalay Bay suite into an open-air concert crowd, killing 58 people and injuring more than 800.
They accuse MGM Resorts, which owns the high-rise hotel and owned the concert venue across Las Vegas Boulevard, of failing to adequately protect the 22,000 people attending the Route 91 Harvest Festival.
They point to findings that the shooter, Stephen Paddock, spent several days amassing an arsenal of assault-style weapons and ammunition in the two-room suite.
Fox News’ Greg Norman and The Associated Press contributed to this report