Ebb & Flow

Whether it was a phone company employee or a NASDAQ staffer who plugged in the margarita blender a bit early on Friday, the trading snafu that struck the electronic exchange on Friday created real headaches for investors and companies trying to divine second quarter stock performance.

The last business day of the quarter was thrown into turmoil as NASDAQ trading was interrupted at 2:30 PM EDT by a network outage. It didn't help that the blunder came on the heavy trading day, when portfolio managers apply the final window dressing to their quarterly returns. The snafu also may have hindered traders trying to match their portfolios to reflect newly rebalanced Russell 2000 Indexes, which were scheduled to begin trading today...