"Regulators favor patent pools to encourage innovation in industries where overlapping patents and excessive litigation suppress innovation. With patent pools, member firms share patents freely with each other and offer one-stop licenses to outside firms. Thus patent pools are expected to promote innovation by reducing litigation risks for pool members and lowering transaction costs for outside firms. We examine this prediction at the example of the first patent pool in U.S. history, the Sewing Machine Combination (1856-1877). Our data confirm that pools reduce litigation risks for members and that pool members patent more in the years leading up to the pool. Pool members, however, patent less as soon as the pool is established and only resume patenting after the pool dissolves."