(Adds background, power prices, Dominion stock price)
By Scott DiSavino
June 8 (Reuters) - Dominion Energy Inc said on Thursday that it will "continue assessing" its investments in Connecticut after the state's House did not pass a bill that would allow the state to buy electricity from Dominion's Millstone nuclear power plant.
Millstone is one of several nuclear plants in the U.S. Northeast and Midwest that could close before their licenses expire, industry analysts say. They have said weak power prices have made it uneconomical to operate some plants without state support.
"We were disappointed that the House chose inaction. We will continue assessing our investments in Connecticut while advocating for needed action," Dominion spokesman Chet Wade said in a statement.
On Wednesday morning, Connecticut's Senate passed a bill allowing the state to buy power from the 2,088-megawatt Millstone plant. However, that evening, the House withdrew the measure hours before the legislative session ended.
Ken Holt, a spokesman at Millstone, said on Wednesday it was premature to speculate on whether the company would shut the plant, noting Dominion has already sold 85 percent of the power Millstone is expected to generate in 2017. Purchasers include hedge funds.
Holt said Dominion has not sold Millstone's power beyond this year because it was waiting to see where prices would go and the outcome of legislation. Connecticut is one of several states that have explored ways to boost their nuclear plants' revenues to keep them in service to preserve benefits they provide, including carbon-free energy, jobs, taxes and energy diversification.
In 2016, New York and Illinois adopted rules to subsidize some reactors that were in danger of closing due to cheap and abundant shale gas driving electricity rates lower.
Several companies with mostly gas-fired plants have gone to federal court to challenge those rules. Plaintiffs include NRG Energy Inc, Dynegy Inc and Calpine Corp.
Ohio, Pennsylvania and New Jersey are also considering similar rules to protect their reactors.
Next-day power prices in New England averaged $35.40 per megawatt hour in 2016, the lowest in the Reuters data series beginning in 2001. That compares with a 10-year average of $59.02.
In early Thursday trading, Dominion shares slipped about 0.9 percent to $79.78. The stock hit an all-time high of $81.62 on June 2, according to Reuters data going back to 1983.
Reporting by Scott DiSavino; Editing by Chizu Nomiyama and W Simon