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Further selling if this level is breached: Cashin

Investors interested in the direction of the stock market should watch key technical levels, veteran trader Art Cashin told CNBC on Wednesday.

Specifically, he pointed to the 1,926 level on the S&P 500 (^GSPC) index and 1,077 on the Russell 2000 (^RUT).

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"If we take out the Russell and take it out rather severely, we have a problem because there's nearly a year-long chart formation, a rectangle that would be wiped out and that would probably call for further selling," he said. "So a retest of Thursday morning's low is likely and we better study for the test."

Separately, the Federal Open Market Committee, the monetary policymaking body of the Federal Reserve , is expected to release the minutes from its September meeting at 2 p.m. ET. Cashin, though, says it's unlikely the Fed will raise interest rates any time soon.

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Cashin also said traders continue to watch mounting geopolitical tensions, especially the advance of the Islamic State terrorist group in Iraq and Syria.