The new key level for crude oil

Trading Nation: Can crude keep rising?
Has the bounce run its course?
High valuations, poor performance

Traders seem to be pinning expectations for oil prices to one specific number now that crude has staged an impressive comeback this year.

In the past month, WTI crude oil has rallied more than 20 percent, taking the commodity into positive territory for the year. But technician Craig Johnson of Piper Jaffray said he's waiting for crude to hit $40 before changing his bearish tune.

"It's going to take a close above $40 to reverse a long-term downtrend we've seen," Johnson said Friday on CNBC's "Power Lunch. " "At this point in time, I'm skeptical."

Johnson isn't the only one setting store by the $40 level in crude oil. Options that allow their owners to buy crude oil for $40 or above have seen notably more buyers and sellers compared with all other strike prices. Calls that expire in May and June have higher levels of open interest at $40 than at any other level. On Monday, call contracts that expire in April saw the highest trading volume in the $40 strike.

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Before crude oil reaches that key level, Johnson said he foresees another wave of pain for the commodity.

"The recent price action we've seen looks to me to be just a relief rally," he said. "My thoughts are there's one more final washout. Maybe oil trades all the way down to $15 to $17 in a final capitulation."

However, Nicholas Colas of Convergex said improving sentiment on the global economy may be enough to boost oil prices in the near term.

"I think there's reason for optimism," he said Friday in a "Trading Nation " segment. "The markets suffered under so much worry about global economic growth, [that now] you could see some further interesting upside in oil and in energy stocks as well."

Contributing to the optimism are better-than-expected job growth for February and reassurance from Chinese officials on the country's economic growth prospects, Colas said.

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