If an additional competitor reduces output per firm in a homogenous Cournot-oligopoly, market entry will be excessive … the excessive entry prediction. Tax evasion raises the number of firms in market equilibrium and can alter their welfare …-maximizing number. In consequence, evasion can aggravate or mitigate excessive entry. Which of these outcomes prevails is determined by …

economic theory prescribes that the advertising volume can be optimally reduced by levying a tax on ads. However, making use of … recent advances in the theory of Industrial Organization and two-sided markets we show that taxing ads may be …

Standard media economics models imply that increased platform competition decreases ad levels and that mergers reduce … assumptions that there is no advertising congestion and that viewers single-home. Allowing for crowding in viewer attention spans …

. That includes mergers that are known to be unprofitable in the corresponding static equilibrium framework …

oligopoly. We find that in the short run, i.e. when the number of firms in both markets is exogenous, the results concerning tax … under-shifting are more pronounced, potentially to a very large extent. Instead, in the long run under endogenous entry and … exit over-shifting of both taxes is more likely to occur and is more pronounced under upstream oligopoly. As a result of …