Stocks Go Negative

North American stock exchanges have been open for about a half-hour, and the S&P 500 just went negative.

The index is down about 0.1%, trading at 1769, 5 points off the highs of the morning.

Meanwhile, 10-year U.S. Treasury futures are up 0.2%, and the yield on the 10-year note is at 2.62% (down 2 basis points from yesterday's close), while gold is down 0.9%, trading at $1306 an ounce.

So far, it's been a pretty crazy morning.

We had a surprise rate cut by the ECB, which sent the euro plunging and European stock indices - as well as U.S. futures - higher.

Then, at 8:30 AM ET, we got both the first look at Q3 U.S. GDP growth (which unexpectedly accelerated) and the latest initial jobless claims (which fell, but came in just slightly above expectations).

Now, all the buzz is about the Twitter IPO, which is happening today. Preliminary indications suggest shares will trade in the $40-44 range upon opening, well above last night's $26 pricing.