possibility to expand the target with combined sales force, thus providing advantages on a long-term basis for companies. In the pharmaceutical industry Co-promotion agreements are commonly used by pharmaceutical companies to improve the marketing and product penetration in particular countries. Since the 2000s co-promotion started to play an important role in the pharmaceutical industry. Co-promotion plays a major role in the pharmaceutical industries because in today's market, pharma companies are in a situation of falling productivity. Accessing to new products through association with biotech companies allows pharma companies to expand their influence and guarantee their success over the market. The industry itself has a complex manufacturing and as a consequence a less competitive market. Therefore, those companies prefer to make co-promotion agreements because they can be able to have a more stable revenue stream which is strategically preferred. Co-promotion is also considered as an advantage for emerging companies in terms of capital infusions, sharing of risks for product development and for regulatory or commercialisation expertise. While it has been usual for biotech firms to receive between 5%and 10% of the revenues incurred in mutual projects, this number has grown in some cases to around 50% (Zanetti and Steiner 2001). A specific example Merck and Agensys had an agreement in order to promote a cancer drug, it has cost $17.5 million in upfront payments and up to $11.5 million over the next year in milestone payments to develop the AGS-PSCA drug for prostate cancer. In this agreement Merck will have the responsibility for commercial manufacture and worldwide clinical development while Agensys will have equal participation in these developments. In addition, Agensys will work on providing a cancer treatment drug at an earlier stage with a smaller chance of risk through milestone payments. The development sharing will help both companies to be more productive. Other examples Exelixis in collaboration with GlaxoSmith-Kline (helped to be positioned ad number 2 in the U.S). Genta in collaboration with Aventis. Monsanto with Pfizer for Celebex (total upfront payment of $85 million). Neurocrine in collaboration with Pfizer. Warner-Lambert and Pfizer for Lipitor. Glaxo- SmithKline and Janssen for Paxil. Pharmacia & Upjohn (now part of Pfizer) and Janssen Pharmaceuticals to co-promote Pharmacia's antidepressant Vestra the agreement recovered 27% of the company's total first-half revenues ($6.2 billion), and 44 percent of its total pharmaceutical sales ($3.7 billion). For Pfizer case the agreement was 18% of the company's revenues ($4.4