NEW YORK ( TheStreet) -- Splunk ( SPLK) fell in extended-hours trading Thursday after the big data company raised its full-year revenue outlook, but forecast negative second-quarter operating margins as it continues to invest heavily in data platform, content and Software-as-a-Service offerings. At last check, shares were down 4.02% to $43.40 in after-hours trading. "We are off to a strong start in the first quarter and I'm pleased with our new customer acquisition and financial performance," chairman and CEO Godfrey Sullivan said in a statement. "Years of investment and product innovation have resulted in recognition that Splunk is disrupting the enterprise software space." In its first-quarter earnings release, Splunk said it expects full-year revenue of between $266 million and $274 million, up from its Feb. 28 forecast of $260 million to $270 million. Analysts polled by Thomson Reuters on average were expecting full-year revenue of $270.61 million. Operating margin forecasts for the year were unchanged at roughly breakeven. For the current quarter, the company predicted revenue of between $61 million and $63 million, versus the average analyst estimate of $61.65 million. Splunk predicted second-quarter operating margin of between negative 4% and negative 6%. For the first-quarter ended April 30, Splunk posted in-line loss per share of 6 cents on a 54% year-over-year increase in revenue to $57.2 million. The consensus revenue target on Wall Street was $54.03 million. During the first quarter, Splunk signed more than 350 new enterprise customers, ending the quarter with about 5,600 customers worldwide. Follow @atwtseWritten by Andrea Tse in New York >To contact the writer of this article, click here: Andrea Tse.