(CNBC) — U.S. stocks closed lower Monday, as investors looked ahead to the week's scheduled Fed meeting and the upcoming U.K. vote on whether to leave the European Union.
The latest Brexit poll, released midday ET Monday by The Guardian, showed a gain in the "leave" camp over the "remain."
"The unknown is really again creating that anxiety right now," said Daniel Deming, managing director at KKM Financial. "There's no reason to see implied volatility jumping like it is when realized volatility is very subdued."
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