We briefly survey several insights about value and revenue maximization in multi-object auctions and apply them to the German (and Austrian) UMTS auction. In particular, we discuss in detail the exposure problem that caused firms in Germany to pay almost Euro 20 billion for nothing.

Agents in a finite two-sided market are matched assortatively, based on costly investments. Besides signaling private, complementary types, investments generate direct benefits for partners. We explore quantitative properties of the equilibrium investment behavior. The bilateral external...