GUPPI: The Gross Upward, Pricing Pressure Index, was proposed by Salop and Moresi (2009) and Moresi (2010).The GUPPI provides an estimate of the merged firm’s incentive to raise prices. However, it does not directly estimate price rises after a merger. It is usually compared against an assumed ‘tolerable’ threshold, such as 5% or 10%. If GUPPI is larger than this threshold, it is accepted that the merger could raise competition concerns. It does not take into account the efficiency gains from a merger.
UPP:The UPP test was developed by Farrell and Shapiro (2010).The UPP test does not estimate the magnitude of the price increase. It only shows the likelihood of a post-merger price increase.
IPR:The Illustrative Price Rise (IPR) tests directly predict the magnitude of price increases after a merger (Shapiro, 2010).Unlike GUPPI and UPP, the IPR tests require information, or assumptions, on the functional form of demand and the pass-through rate.