The State Street Investor Confidence Index reading of the outlook of institutional investors showed a four-point decline in September to 88, down from 92 in August. In North America, the drop was more pronounced; the confidence level fell 7.3 points to 87.9 from August’s reading of 95.2.

“This month’s decline in global investor confidence is somewhat surprising, in light of the meaningful rally in risky assets since the last data release,” said Harvard University Professor Ken Froot, who helped develop the index with State Street Global Markets. It looks at the actual buying and selling patterns of institutional investors with a particular eye to equity exposure.

“Looking at the numbers more closely, however, we see that the decline is driven largely by North American investors; elsewhere we see a much more upbeat mood," Froot said.

Investors’ outlook was dampened by the softening of the U.S. economy over the summer, Froot said. By comparison, the markets in Australia, Canada, New Zealand and Sweden were “resilient,” he said.

As far as actual holdings, institutional investors sold U.S. and European-ex U.K. securities, and moved into emerging markets and stocks, noted State Street Director Paul O’Connell. “Thus, this month’s numbers reflect a reevaluation of relative country prospects by investors, rather than a wholesale reduction in risk appetite.”