Investing.com -- Wednesday's sharp gap-up open in U.S. equities is a rare technical event, according to BTIG, with the firm stating in a note that the next few days will be decisive in determining whether stocks are headed meaningfully higher or lower.

Analyst Jonathan Krinsky identified two competing historical signals that point in opposite directions, arguing that a neutral stance is warranted until the market shows its hand.

On the bullish side, BTIG found just five prior instances since 2003 where the S&P 500 ETF SPY posted a "true gap" of at least 1.5%, which is defined as the intraday low being at least 1.5% above the prior day's intraday high.

Forward returns were positive in every case across two, four, eight, and 12-week horizons, with median four and eight-week returns of 6.09% and 9.1%, respectively. Four of the five gaps remain unfilled to this day.

The bearish signal is equally stark. Since 2003, SPY has opened above both its 50 and 200-day moving averages while closing below both the prior day just three other times, in December 2007, December 2015 and December 2018.

"Those three periods saw immediate declines of -13%, -16%, and -13% over the next few weeks," Krinsky wrote.

BTIG said the resolution will likely come quickly. "In the bullish cases, the market made higher-highs in the next few days. In the bearish cases, the high was essentially the day of the gap and then swiftly moved lower," Krinsky wrote.

The firm flagged software and business development companies as lingering concerns regardless of which scenario plays out.