CiscoShares of networking equipment maker Cisco Systems (CSCO) plunged Thursday after the company's forecast for fiscal second-quarter earnings came in lower than expected.

The company said it expects second-quarter sales to fall between $10.1 billion to $10.3 billion. Analysts surveyed by Bloomberg News projected sales of $11.1 billion

For the quarter ended Oct. 30, Cisco reported earnings of 34 cents per share, up from 30 cents per share a year earlier. Revenue rose 19% to $10.8 billion.

During an analyst conference call Wednesday, CEO John Chambers noted that the company saw "several challenges in the quarter" including "certain categories of our public sector segment, certain product in our service provider segment, and to a limited extent, Europe, in terms of business momentum."

The news sent Cisco shares down more than 16% Thursday.

Increase your money and finance knowledge from home

What Is Your Risk Tolerance?

Answer the question "What type of investor am I?".

View Course »

Forex for Beginners

Learn about trading currencies and foreign exchange transactions

View Course »