Investor confidence rose 8.7 points in February, according to State Street Global Markets index.

The Global State Street Investor Confidence Index rose 8.7 points to finish at 94.8 for the month. Boston-based State Street Global Markets releases the monthly index, which measures confidence based on the buying and selling patterns of institutional investors.

Increased confidence by North American institutions, which rose 13.9 points, followed by optimistic European institutional investors was the main force behind the increase.

Paul O’Connell of State Street Associates and Kenneth Froot, a Harvard University professor, developed the Investor Confidence Index. The index assigns a precise meaning to changes in investor confidence: the greater the percentage allocation to equities, the higher the confidence. It differs from survey-based measures in that it is based on actual trades, as opposed to opinions, of institutional investors.

“The pronounced increase in North American investor confidence is noteworthy, as it represents a 19-month high for that regional index,” says O’Connell.