Facebook shares sank nearly six percent on opening Thursday, leading the markets lower in starting trade also hit by poor earnings from Dow Chemical.
Six minutes into trade, the Dow Jones Industrial Average was down 27.41 (0.2 percent) to 13,883.01.
The broad-based S&P 500 dropped 9.5 points (0.63 percent) to 1,498.34.
The tech-heavy Nasdaq Composite fell 2.05 (0.07 percent) to 3,140.26.
The drop in shares came as social networking giant Facebook reported a big fall in year-over-year earnings and signalled higher costs as it invests in data centers.
Dow and UPS also came in with weak results, each reporting quarterly losses.
The results followed Wednesday's US economic report that showed the economy contracted by 0.1 percent in the fourth quarter last year.