This is the most important level to watch on the S&P 500 right now

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Everyone is looking at the S&P 500's 200-day moving average. There's another key support level that could provide a clearer signal of market distress.

If the market does decline further, the most important support level will be 2,581 on the S&P 500. That was the closing low on Feb. 8 and April 2. Any meaningful close below that level would raise a big red flag on the stock market over the near term.

When support and resistance levels are broken, it tends to indicate that the buyers have run out of ammunition or sellers have run out of stock to sell. The asset then sees a major move once those levels are broken. Moving averages help smooth out the erratic moves we see from time to time in the markets, so they are not quite as important to a traditional technician.

The other thing to watch is the lack of volume in the market. If you look at the "double bottom" that took place in 2015 and 2016, both lows were accompanied by a jump in volume. Getting that big jump in volume during the retest of lows told investors that some capitulation had taken place and that the market had finally become washed-out.

This time around, volume did not jump at all. In fact, it was very, very low. That suggests there is not enough fear in the marketplace to create a sustainable low right now.

The likely reason is that investors hope the earnings season will turn things around. If that's the case, they likely don't want to sell ahead of that.