Shares of the St. Louis company rose 12.93% to $29.27 on Friday. Aegion's stock, on track to close at the highest price since February 2011, has soared 56.5% over the past three months.
Last month, the company had agreed to be acquired by affiliates of investment firm New Mountain Capital, for $26 a share in a deal valued at $963 million.
The company's board was evaluating the unsolicited proposal in consultation with its independent financial and legal advisors, Aegion said, without identifying the bidder.
Aegion's board hasn't yet determined whether the new bid is a “superior proposal” to the offer made by New Mountain Capital.
"There can be no assurance that any transaction or definitive agreement will result from this proposal," the company said.
Earlier this week, Aegion reported a fourth-quarter loss of $5.6 million, or 18 cents a share.
The company posted revenue of $205.5 million, a drop of 8.6% from $225 million in the year-ago quarter.
“Our improved performance from continuing operations in the face of unprecedented market disruption demonstrates the resiliency and commitment of our employees globally as well as the critical need for our products and services,” said Aegion President and Chief Executive Charles R. Gordon in a statement.
“As we move forward, we are continuing to advance our strategy of providing differentiated pipeline rehabilitation and protection technologies for the benefit of public health and the environment," he added.