Stock futures fell in morning trading on Thursday as the market looks set to give back some of its gains over the holiday week.

Dow Jones Industrial Average futures fell 150 points. S&P 500 futures fell 0.3% and Nasdaq 100 futures fell 0.3%. The market was closed on Wednesday for Christmas Day.

The major averages could see their first day of decline this week after consecutive gains. So far this week, the S&P 500 is up 1.8%, while the Dow has gained about 1%. The strong rally in the megacap technology sector pushed the Nasdaq up 2.3% for the week so far.

Investors were enthusiastic about the so-called Santa Claus rally, which takes place on the last five trading days of the year and the first two in January. According to LPL Research, since 1950, the S&P 500 has returned an average of 1.3% over that period, far exceeding the market’s seven-day average return of 0.3%. Thursday is the second day of the Santa Claus rally.

“Santa Claus Rally could be alive and well. We’ll see, or it could be difficult,” Michael Zinn, senior portfolio manager at UBS Wealth Management, said on CNBC’s “Squawk Box.” “It’s a sleepy time of year. The institutions don’t really act. It’s a little more retail driven. So what happens at the end of the year is not necessarily an indicator of how January and February will perform.”

Initial jobless claims data on Thursday morning could provide insight into the state of the labor market.

The S&P 500 is up 0.1% since the start of the month, while the tech-heavy Nasdaq has gained 4.2% thanks to strong gains from Tesla, Apple and Alphabet. However, the blue-chip Dow index has now fallen about 3.6%, putting it on track for its worst month since April.