How often is SPX value updated.

Beginning in 1986, the index value was updated every 15 seconds, or 1,559 times per trading day, with price updates disseminated by Reuters.

Is this still accurate?

 

No. It's much faster now. (CBOE data)

 

TradeStation $SPX.X CBOE feed updates once a second, then for some reason 1261 times the last minute @ 400pm EDT

 

Thank you for the replies.