Stocks were taken for a wild ride on Thursday that showed just how important finding a treatment for the coronavirus is for Wall Street.

The Dow Jones Industrial Average closed just 39.44 points higher, or 0.2%, at 23,515.26. Earlier in the day, the Dow rallied more than 400 points. The S&P 500 dipped 0.1% to 2,797.80 while the Nasdaq Composite closed just below breakeven at 8,494.75. Both the Nasdaq and S&P 500 were up more than 1% at their session highs.

The Financial Times said — citing documents accidentally published by the World Health Organization — that Gilead Sciences' drug remdesivir did not improve patients' condition or reduce the coronavirus pathogen in their bloodstream. Those findings, according to the report, came from a clinical trial in China.

Gilead took issue with the report, saying: "Because this study was terminated early due to low enrollment, it was underpowered to enable statistically meaningful conclusions. As such, the study results are inconclusive, though trends in the data suggest a potential benefit for remdesivir, particularly among patients treated early in disease."

Equities attempted a rebound on the back of Gilead's statement before closing along the flatline. Gilead Sciences shares closed 4.3% lower.

The report and Gilead's subsequent statement came a week after STAT News reported that Chicago patients taking remdesivir to treat coronavirus were recovering rapidly from severe virus symptoms. That report lifted market sentiment, sending stocks sharply higher.

"Any sort of treatment is key for people to getting people back out into the world," said Kim Forrest, founder of Bokeh Capital, on CNBC's "The Exchange." "When the results were announced of the trial last week, you could see the market react and it was a sigh of relief that, if I get this, I may not die."