On New Year's Day, NYSE Euronext (NYS: NYX) announced its quarterly changes to the circuit-breaker triggers. These are safeguards against market panics that would put a temporary stop to NYSE trading if the Dow Jones Industrial Average (INDEX: ^DJI) fell too far, too fast.
The trigger levels have generally stabilized over the last year, in concert with the Dow's overall direction:
Level 1 Halt (generally a 1-hour trading pause)
Level 2 Halt (generally a 2-hour trading pause)
Level 3 Halt (no more trading that day)
Source: NYSE press releases.
But this update came with a surprise: The NYSE will switch its trigger calculations trom the Dow to the broader S&P 500 (INDEX: ^GSPC) index on Feb. 4.
The exchange did not say what brought on this sudden and previously unannounced change in philosophy. Both the Dow and S&P 500 indexes are managed under the S&P/Dow Jones Indices umbrella, which is a joint venture between Dow Jones owner CME Group (NAS: CME) and S&P manager McGraw-Hill (NYS: MHP) .
The article NYSE Circuit Breakers Move From Dow Jones to S&P 500 originally appeared on Fool.com.
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