The Dow went through nearly three weeks of triple-digit gains and losses during that month, a rough ride that made even hardened Wall Street traders nauseous.
"All we're doing now is worrying," Ablin said.
Wall Street is also looking to next Friday, Oct. 4, when investors get the September jobs report. If hiring is strong enough, the Federal Reserve could decide to start pulling back on its economic stimulus at a two-day policy meeting later in the month.
At the end of its last meeting on Sept. 18, traders had expected a small cut in the Fed's $85 billion monthly bond purchases, which are aimed at keeping long-term interest rates low to encourage borrowing. When the Fed kept its bond-buying intact, the Dow and S&P 500 index soared to all-time highs. Wall Street celebrated that the central bank would keep borrowing rates as low as possible.
But the Fed's decision also left traders worried that the economy wasn't healthy enough to grow without the Fed's help.
Investors did get an unexpectedly positive August durable goods report on Wednesday. Orders for long-lasting manufactured goods rose 0.1 percent last month, following an 8.1 percent decline in July.
Among stocks making big moves:
JC Penney fell $1.78, or 15 percent, to $10.12, as more Wall Street analysts continued to downgrade the department store chain's outlook. An analyst at JPMorgan Chase said JC Penney might right out of cash by next year.
Mako Surgical soared $13.29, or 82 percent, to $29.46 after medical technology company Stryker said it would buy Mako for $1.65 billion, or $30 per share.
Ascena Retail Group shares jumped $2.74, or 16 percent, to $20.06. The parent company of Lane Bryant, Dressbarn and Maurices, reported results that were significantly better than financial analysts expected in its most recent quarter.