Nasdaq OMX halted trading on the Nasdaq Options Market on Friday after a "significant increase" in orders flooded the system, the exchange said.
The Nasdaq decided to cancel all orders on the book as of 10:36 a.m. EDT, and keep trading halted through the end of the day.
"A significant increase in order entries inhibited the system's ability to accept orders and disseminate quotes on a subset of symbols, which resulted in the NOM halt," the exchange said.
A source familiar with the situation told CNBC that there was no indication that the increase in order entries was related to any nefarious activity, like high-frequency traders trying to mess with the system. The source was less sure if it might be due to some non-nefarious activity, like an order gone wild.
It's the second technical problem to halt options trading on the index this week.
On Tuesday, several well-known options indexes were
Nasdaq has faced criticism of its handling of the much-touted Facebook IPO last year, in which a flood of orders overwhelmed the system, leaving many traders unsure whether their trades were executed.
(Read more: To avoid Facebook chaos, NYSE runs Twitter IPO test)
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