Thursday proved that when it comes to the stock market, what goes up often comes right back down again -- at least for a while. After Wednesday's historic quadruple-digit jump in the Dow Jones Industrial Average, investors appeared to return to their pessimistic state on Thursday morning, and the Dow gave back more than half of its gains as market participants fretted about trade, slowing global economic growth, and geopolitical factors. Yet by the end of the session, investors seemed to get their grove back, and most stock indexes finished the day firmly in the green. Moreover, some companies managed to send their shares sharply higher with good news. Energous (NASDAQ:WATT), Siebert Financial (NASDAQ:SIEB), and PQ Group Holdings (NYSE:PQG) were among the best performers. Here's why they did so well.

Energous celebrates a product approval

Shares of Energous blazed higher by 54% after the maker of systems for wireless device charging announced that one of its products had received approval from a key regulator. The Federal Communications Commission has approved the sale of personal sound amplification products sold by hearing-aid specialist Delight that use Energous' WattUp wireless charging technology, and Energous says that it expects the products to be available to consumers during the first quarter of 2019. CEO Stephen Rizzone is excited, noting that despite delays, "the customer funnel is robust, and we believe this is the first of many WattUp-enabled consumer electronic products in a number of growing vertical markets that will be going into full production in 2019."

Brick building with Energous logo on the side.

Image source: Energous.

Siebert looks to climb out of its funk

Siebert Financial saw its shares rise 12%, continuing upward momentum that has produced gains of more than 20% in just over a week's time. The financial advisory services provider has worked on a variety of projects ranging from robo-advisory services to the cryptocurrency markets, and some believe that Siebert's offerings stand to benefit from rising volatility in the financial markets. After having hit new lows for the year, bitcoin and other cryptocurrencies have rebounded sharply, and optimists also think that could give Siebert new opportunities as well.

PQ pays down some debt

Finally, shares of PQ Group Holdings rose 7%. The maker of specialty chemicals and related materials said that it intends to pay down an extra $55 million against its term loan facility, bringing its total debt reduction for 2018 to about $135 million. Investors have been worried about PQ's debt load, which totaled $2.2 billion as of Sept. 30. Yet PQ has rate caps in place on the portion of its debt that's subject to variable interest rates, and its effort to direct cash flow toward strengthening its balance sheet is a prudent move -- especially as the industrial economy starts to face tougher headwinds.