"Thus demand for patents appears to be very high in information technology, but in fact patents play a far lesser role than they do in pharmaceuticals. IT companies want "freedom to operate" in order to build complex products and services without being blocked by the many patents that belong to others. They assemble large portfolios to be used defensively if and when they are threatened with infringement actions by competitors. This deterrent effect is reminiscent of a nuclear arms race, and is often referred to as "mutually assured destruction." Large companies commonly cross-license with each other, often with balancing payments to adjust for the size of their respective portfolios. Cross-licensing is problematic for a field like software, however, where there are a large number of different-sized, differently-situated companies."