There was no particular news out of the company, but "people familiar with the matter" leaked an important update about the utility's strategic plans. Investors were not pleased.
Activist investor Elliott Management has been prodding Evergy's leadership to increase shareholder value. In March, the two companies came to an agreement that included the appointment of two new independent directors.
The biggest part of the deal, however, was that Evergy would set up a committee to perform "a comprehensive, independent review to identify and recommend ways to enhance shareholder value, including through a potential strategic combination or a modified long-term stand-alone operating plan and strategy." Basically, Elliott got board representation and then asked Evergy to find a buyer and sell itself.
Today, however, news leaked that Evergy had decided that it would not be selling itself. It reached out to several potential buyers, according to Bloomberg, but believed that there was more value to be created by charting its own stand-alone course.
As is often the case when a company is rumored to be selling itself, investors got excited by the idea. Buyouts often come with premium prices, so that's not an unreasonable response. However, when the rumor that no deal was going to take place leaked out, Wall Street dumped the shares, which is also a common investor response in such situations.
The board still has to vote on the committee's recommendation, according to Bloomberg, so this fight isn't over yet. Even if the board accepts the plan, it's highly likely that Elliot will continue to agitate for change.
In other words, there could be more news-driven volatility here in the near future. Evergy is probably best left to special-situation investors for now.