Jan 5 (Reuters) - U.S. stock index futures fell sharply on Thursday after a greater-than-expected rise in U.S. private employment fueled worries about the Federal Reserve's rate hike trajectory.

The ADP National Employment report showed private employment rose by 235,000 jobs in December, after rising by 127,000 jobs in November. Economists polled by Reuters had forecast an increase of 150,000 jobs.

At 8:16 a.m. ET, Dow e-minis were down 97 points, or 0.29%, S&P 500 e-minis were down 10 points, or 0.26%, and Nasdaq 100 e-minis were down 28.5 points, or 0.26%. (Reporting by Amruta Khandekar and Ankika Biswas in Bengaluru; Editing by Shounak Dasgupta)