STOCKS TANK, TWITTER SURGES, ECB SHOCKS THE MARKET: Here's What You Need To Know

There was a lot of news today.

First, the scoreboard:

• Dow: 15,623.7, -123.1, -0.7%
• S&P 500: 1,750.5, -19.9, -1.1%
• NASDAQ: 3,865.7, -66.1, -1.6%

And now the top stories:

• Today's action really started at 7:45 a.m. ET when the European Central Bank unexpectedly announced a shocking 25 basis point cut to its benchmark interest rate. "Draghi acknowledged falling inflation, saying the decline was stronger than expected and that inflation should remain at low levels in the coming months as underlying price pressures remain subdued," reported BI's Matthew Boesler. Markets reacted violently to the move with the euro collapsing and stocks spiking.
• We got our first reading of Q3 GDP today, and at first glance it looked much stronger than expected. U.S. GDP growth unexpectedly accelerated to 2.8% from 2.5% in Q2. This was much stronger than the 2.0% reading expected by economists. But personal consumption growth slowed to 1.5%, which was a bit worse than the 1.6% rate expected.
• Everyone immediately pointed to the larger-than-expected boost from inventory accumulation, which added 0.8 percentage points to the headline number. "While some analysts are citing the inventory build as reason to discount the overall growth figure and worry about downside production risks in the current quarter, we do not share this view," said Deutsche Bank's Joe LaVorgna. "First of all, the continued health of the various production surveys, such as the ISM and regional PMIs, suggests that the factory sector is not pausing to rebalance. The reason for this is likely due to the fact that order backlogs continue to expand and currently stand at post-recession highs. Inventory levels remain extremely lean: While the economy has been in expansion mode since mid-2009, inventories only rose above their pre-recession peak last quarter."
• Regarding the disappointing consumer spending number, Bank of Tokyo-Mitsubishi's Chris Rupkey was left scratching his head. "What is up with consumers anyway?" he asked. "Washington uncertainty or payroll tax holiday expiration taking the wind out of their sails? That explanation does not make sense as consumer spending 1.7% in the third and fourth quarter last year before the tax cut expiration, and 2.3% Q1, 1.8% Q2 and now 1.5% Q3 this year 2013. The relative lack of consumer spending bugs the Fed too, something for them to puzzle over, why consumer spending is averaging 1.8% since last summer and not a more satisfactory 3%-plus as they say. There are certainly more of them, consumers, with 2.3 million new private payroll jobs being created the last year, 2.3 million additional paychecks- 114 million people in total. Nothing adds up here."
• "Real final sales, which are a good measure of underlying demand because it backs out the inventory contribution, came in at 2.0%," noted Bank of America Merrill Lynch's Joshua Dennerlein. "In other words, the economy remains stuck in the mud. We believe that the Fed needs to see an acceleration in growth before they will begin tapering."
• Twitter's IPO hit today, and it was huge. It priced at $26 per share last night, and it opened at a whopping $45.10.
• Twitter also got its first big analyst downgrade. "We are downgrading our rating on Twitter to SELL as opening trading levels on Twitter fall well above a 15% range above our price target of $30," said Pivotal Research's Brian Wieser. "At a price in the high 20s or low 30s (which seems to us a reasonable price range) and based on our best assessment of Twitter's growth prospects and appropriate drivers of our discounted cashflow valuation (all determined on a basis that is relative to the variables we use to value Google and Facebook), Twitter would be fairly valued."
• Groupon announces earnings after the closing bell. Follow the announcement live on BusinessInsider.com.
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