• Both Greenlight Capital and the Greenlight Capital Offshore fell by 6.2 percent in February, according to David Einhorn's monthly update to investors, as seen by CNBC.

• The fresh round of losses extends the hedge fund's decline in 2018 to more than 12 percent.

• Greenlight Capital has been under-performing the S&P 500.

David Einhorn's Greenlight Capital GLRE suffered another round of losses in February — extending the hedge fund's decline in 2018 to more than 12 percent.

Both the main Greenlight Capital fund and the Greenlight Capital Offshore fell by 6.2 percent in February, according to Einhorn's monthly update to investors, which was obtained by CNBC.

Greenlight Capital and Greenlight Capital Offshore declined by 6.6 percent and 6 percent , respectively, in January.

The hedge fund has been under-performing the S&P 500 in 2018.

The S&P had its best January in two decades, rising 5.6 percent that month. It subsequently lost around 3.8 percent in February, to bring the year's gain to 1.8 percent.

Einhorn had said in a conference call last week that the company has "never underperformed like this."

— CNBC's Scott Wapner contributed to this report.

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