At this juncture, the U.S. stock market just loves positive economic surprises. Each one creates a sense of hope that the economic recovery is gathering momentum that will continue to build. If China's reopening experience is any indication, however, that view may soon be put to the test.

The Citi Economic Surprise Index is a gauge of how economic data surprises are tracking relative to economists' consensus estimate. The dividing line between negative surprises and positive surprises is 0.0. A trend line, though, can be just as influential in shaping expectations.

A surprise index might be below 0.0, but an upward trend implies the negative surprises have been less negative. Conversely, a surprise index that is above 0.0 and trending higher implies the positive surprises are handily beating consensus estimates.

What's evident in the chart below is that the U.S. data have been filled with positive surprises of late. Meanwhile, ever since Italy loosened its restrictions in early May, economic surprises in the eurozone have been less negative.

The same can be said for China for the most part since it lifted its lockdown restriction on Wuhan in early April. Something that can't be missed about China in the chart below either, however, is that its surprise momentum has been waning since June 12 or roughly two months after the Wuhan lockdown ended.

Why might this be important? Well, China emerged earlier from the coronavirus shutdown than both the U.S. and the eurozone, but if it's losing upside surprise momentum already, it could suggest the U.S. might soon lose its positive surprise momentum, too.

Incidentally, today is roughly two months since Texas, Florida, and Georgia forged ahead with reopening efforts, and as everyone knows by now, some of those efforts have been paused or rolled back because of a rapid increase in corornavirus case counts and positivity rates. Separately, New Jersey and New York City have preempted plans to allow indoor dining, and California has announced that it will close indoor dining and bars in 19 additional counties.

The momentum of the reopening effort, then, should inevitably lose some of its momentum.

That could create some negative surprises in the data that flatten the curve on positive economic surprises out of the U.S. and squelch some of the trading luster in the stock market that follows positive economic surprises showing sequential rebound momentum.

Another connection is the loss of positive surprise momentum could create some doubt about a V-shaped recovery, which already seems to be in doubt in the Treasury market, and could serve as another underpinning factor for bond prices.