The Securities and Exchange Commission (SEC) on Thursday issued a guide to private investors on the dangers that identity thieves pose to online broker accounts.

"We are concerned that many investors aren't taking appropriate precautions when accessing their online brokerage accounts," said Susan Wyderko, the SEC's investor education director, in a statement.

Regulators are concerned, the SEC added, that identity thieves are targeting online investors with spyware, other malicious software, and phishing-style spams to hijack user account names and passwords.

The guide can be found here.

"In [the] guide, we offer tips on how online investors can protect their personal information from intruders," Wyderko said.

Among the precautions investors should take, the SEC cited a personal firewall and ignoring e-mails asking for confidential information.