They must not be feeding the right number than, Currently it's showing 1440.12 and -32.87 on the day which puts it off by $1. It does show up in the arbitrage meter when I use NDX so it must be the right symbol. It just doesn't usually match the Ameritrade quote I get. I wonder who calculates it, and how often. The SPX is calculated by the S&P once every 15 secs during market hours and sent out. And the NDX just changed on IB to 1440.32 and -32.67. It's not suppose to change after 4pm. Puzzling.
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