Money transfer company Xoom said $30.8 million was fraudulently transferred to overseas accounts, sending its shares down as much as 17 percent in extended trading.

The company also said Matt Hibbard resigned as chief financial officer effective immediately. Hibbard took over from Ryno Blignaut just last month.

Blignaut will be the acting CFO and chief risk officer, Xoom said in a filing on Monday.

Xoom said employee impersonation and fraudulent requests targeting its finance department were discovered on Dec. 30 and it expected to take a one-time charge of $30.8 million in the fourth quarter ended Dec. 31.

The company said it believes no customer's data or money was involved and its systems were not impacted.

Xoom said it had contacted federal law enforcement authorities who are pursuing a multi-agency criminal investigation on the matter.

Xoom also raised its fourth-quarter revenue estimate to $43.1 million-$43.6 million from $41 million-$43 million.

Xoom's shares closed at $16.89 on the Nasdaq on Monday. (Get the latest quote here.)