Apple's stock fell about 1.2 percent in regular trading, dipping below $600 for the first time since July after hours before recovering a bit.
The success of the offering, however, did not bolster Yahoo, whose stock fell during midday trading, dipping under the $40 mark before partially recovering.
But Mr. Obama got help by starting the clock during the depths of the recession in 2009, when global trade dipped and American exports fell.
Investors were unimpressed by this belt-tightening: The Marconi selloff continued this morning, with the ADRs off another 10% in early trading to dip below the $3 mark.
Facebook's stock began falling in after-hours trading Thursday, dipping below $24.
But trading conditions dipped sharply in the past two months, with order volumes holding up but prices falling.
The shares fell $3.45, to $13.88, in extended trading, after dipping to $13.45 earlier.
Lloyds Bank's latest barometer of business mood found confidence about trading prospects dipped to a three-year low in May.
The company's market share, which normally hovers around 11 percent of daily stock trading volume, dipped several percentage points, as customers rerouted trades to other exchanges.
Seb James, the ebullient chief executive, said trading had dipped after Black Friday but argued this was part of a new pattern resembling two humps of a camel.
