Disclosure and public availability of market related information is referred to as data transparency in electricity markets. There are still several open questions about the extent and quality of optimal market data transparency. Such concerns will be even more sever in emerging smart grids; although proper communication infrastructure facilitates data sharing and disclosure, market designers or microgrid operators should not publish data excessively as it might have negative effects on market integrity or consumers’ privacy. In this paper, we propose a framework to quantitatively measure effects of transparency of bidding data of generating companies on unilateral exercise of market power and short term market price. Simulation results on an actual market (Alberta) indicate that inappropriate disclosure of bids allows generating companies to increase price impressively which in turn increases end user consumers’ expenses. Accordingly, market designers should pay careful attention to their data transparency policies to avoid any kind of manipulations in the markets.

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