For modern technologies, access to intellectual property rights (IPR) is complex because it is fragmented among many owners. The required licensing agreements invoke considerable transaction costs and royalty stacking. Often, it is in the interest of the technology sponsor to ease access to the required IPR. Patent pools have proven useful to achieve this goal. This paper examines the experiences with three generations of patent pools in the optical disc industry. Technology platforms are becoming increasingly complex, which leads to a fragmentation of IPR among many pools and causes new issues. A novel `pool-of-pools¿ can address these.