As encouraging as the market comeback this month has been, Wall Street has little faith in it.

A leveling out of coronavirus hospitalizations, rising hopes for a treatment and a partial reopening of the economy sparked a steep rebound this month, with the S&P 500 popping more than 12%, posting its best month since 1987 and its third-best month ever since World War II.

However, a lack of an all-clear on the pandemic front, coupled with worrisome technical and sentiment indicators, lead many Wall Street pros to believe the market is getting way ahead of itself.

"Beware of the oddity in this bear rally," Andrew Lapthorne, global head of quantitative research at Societe Generale, said in a note Thursday. "Given the overall negative undertone from the economic challenges ahead, the dramatic reversal of global markets after the pandemic lows is more puzzling."

The economic fallout is still unfolding on a daily basis. Stocks dropped Thursday after the latest data showed more than 30 million Americans filed for unemployment over the last six weeks. Meanwhile, the U.S. economy shrank 4.8% in the first quarter, marking the biggest decline since the worst of the financial crisis.

Based on an exhaustive analysis of bear markets in the past 150 years, Societe Generale expects the S&P 500 to end this year at 2,715, a 7% decline from here. The equity benchmark has bounced more than 30% off its March 23 low to 2,939 at Wednesday's close.