By Jonathan Spicer

A spokeswoman for exchange parent Nasdaq OMX Group told Reuters in an email the "erroneous orders" that caused the abrupt plunge "were triggered by orders routed from another exchange."

She did not say which exchange routed the trade orders, but added the decision to cancel trades cannot be appealed.

Transactions at or above $425.29 and at or below $400.52, that were executed between 3:57 p.m. and 4:02 p.m. EST, would be wiped out, Nasdaq said.

The exchange set Google's closing price at $400.52, up 5.12 percent.

A Google spokesman said the company declined to comment on the trading spike.

Earlier, Nasdaq's surveillance arm said in a statement it was investigating "potentially erroneous transactions" in Google shares.

Canceling trades is rare and often embarrassing for exchanges, which some say are more susceptible to problems as they become more electronic. Nasdaq is an all-electronic venue.

(Additional reporting by Eric Auchard in San Francisco; Editing by Gary Hill and Carol Bishopric)