NEW YORK — A private trade group’s measure of the strength of the services sector shrank for the sixth straight month in March and at a faster pace than expected. A services index from the Institute for Supply Management, a Tempe, Ariz.-based trade group of purchasing executives, fell to 40.8 last month from 41.6 in February. Economists surveyed by Thomson Reuters expected the index to edge up to 42. For the full story click here