Please define each of the five forces and then using the information below, perform a five$-$force analysis of the branded pharmaceutical$/$drug industry. Is the branded$-$drug pharmaceutical industry attractive for incumbents?

The pharmaceutical industry consists of firms that develop, patent, and distribute drugs. The major firms and respective market shares are ABBV$-13\mathrm{.}6\%,$ BMY$-12\mathrm{.}9\%,$ JNJ$-12\%,$ and MRK$-9\mathrm{.}3\%.$ The capital intensity is medium as firms acquire lab equipment, instruments, and equipment to develop and produce pharmaceutical agents. Although there are no significant production economies in this industry, there are important economies in research and development. Pharmaceuticals are highly regulated, with extensive government oversight and all drugs must receive approval from the Federal Drug Administration in order to be sold to the consumer. Product differentiation exists as well because firms often sell branded products that are protected by patents. The pharmaceutical firms compete in research and development. However, once a product is developed and patented, competition is significantly reduced. Recently, the increased availability of generic, non$-$branded drugs has threatened the profitability of some drug lines. Once an effective drug is developed, there are usually few, if any, alternatives to that drug. Drugs are manufactured from commodity chemicals usually available from numerous suppliers. Major customers include doctors, insurers, and patients. Recently increased costs have led the federal government and insurance companies to pressure drug companies to reduce their prices.