FACTBOX: U.S. stock circuit breakers/futures limit-downs

NEW YORK (Reuters) - U.S. stock index futures tumbled so sharply on Friday they had to be frozen at several points as global markets plunged on fears the global economy is in the throes of recession.

Below are details of circuit-breaker levels for the New York Stock Exchange and Nasdaq, and limit-down thresholds for U.S. stock index futures set by the CME Group.

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NYSE CIRCUIT BREAKER LEVELS/NASDAQ

These are thresholds at which trading on both the NYSE and Nasdaq is halted marketwide based on single-day declines in the Dow Jones industrial average.

An NYSE circuit-breaker halt was last triggered on October 27, 1997 during a wide-scale market plunge triggered by a financial crisis in Asia.

In unprecedented action, trading was halted twice back then as the sell-off crashed through NYSE circuit breakers, first when the Dow was down 350 points and later as it fell 550 points. They were adopted under measures taken after the 1987 crash, aimed to slow market downdrafts.

Level 1 Halt

An 1,100-point drop in the Dow Jones industrial average before 2 p.m. (1800 GMT) will halt trading for one hour; for 30 minutes if between 2 p.m. and 2:30 p.m. (1830 GMT); and have no effect if at 2:30 p.m. or later unless there is a level 2 halt.

Level 2 Halt

A 2,200-point drop in the Dow before 1:00 p.m. (1700 GMT) will halt trading for two hours; for one hour if between 1:00 p.m. and 2:00 p.m.; and for the remainder of the day if at 2:00 p.m. or later.

Level 3 Halt

A 3,350-point drop will halt trading for the day regardless of when it happens.

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CME GROUP'S U.S. EQUITY INDEX FUTURES DAILY PRICE LIMITS

ARE EFFECTED AS FOLLOWS: