For the biggest power companies in Texas, what doesn’t kill them might actually help them emerge stronger.

Large players in the Texas power market such as Vistra Energy, NRG Energy NRG 4.47% and Exelon EXC 2.65% have all seen their market valuations tank since a winter storm there left the power system in shock. Vistra shaved off roughly $2.7 billion since Feb. 14, right before the blackouts began. That is roughly three times the loss the company expects to incur from this storm. Market capitalizations for Exelon and NRG fell by $10 billion and $328 million, respectively. Both are outsize reactions compared with actual estimated losses: Exelon said the impact—including those from unpaid customer bills—could be $750 million to $950 million before taxes, while NRG Energy reported a relatively muted impact in the order of $100 million.

While these companies have balance sheets to weather the storm, others are on the brink of solvency, opening up the possibility of forced sales at distressed valuations. Just Energy, JE 1.28% a retail energy provider, had said the financial impact from the storm could hamper its ability to continue as a going concern. Another provider, Brazos Electric Power Cooperative, filed for bankruptcy on March 1.

The ultimate dollar impact from the storm is still a moving target. Under existing rules, the grid operator spreads the cost of unsettled bills among other market participants. That number isn’t likely to be finalized for some time as market participants and regulators iron out the fine points.

Representatives of some renewable-energy generators indicated in a filing with the Texas Public Utilities Commission that companies representing at least nine gigawatts worth of capacity would suffer steep financial losses if nothing is done to unwind the peak power prices that were set during the winter storm.

There seemed to be a small possibility that some scarcity payments to power providers—which the grid operator set to the maximum of $9,000 per megawatt-hour for days—could be reversed after an independent market monitor said the grid operator kept prices high for 33 hours longer than warranted. But the Public Utility Commission of Texas on Friday signaled that such a reversal is unlikely, noting that doing so could have unintended consequences, such as harming certain power providers.

Power-market participants that benefited from the peak prices will likely not want to give up their gains. Notably, Australia’s Macquarie Group MQBKY 1.24% bumped up its own guidance in February to reflect the windfall its commodities-trading desk got from capitalizing on gas and electricity volatility in Texas. A number of hedge counterparties to wind farms, typically Wall Street banks, could be owed significant sums, too, under financial agreements that put the generator on the hook for buying power from the market if it can’t operate when called upon.