Two multibillion-dollar deals announced recently are prime examples. Anadarko ( APC) announced a $23.3 billion deal to acquire two competitors last Friday. It plans on issuing debt and equity later in the year to finance the deal. But many debt strategists are concerned about how the financing will proceed , given the uncertain interest rate environment. Univision ( UVN) also could also have problems financing its deal. The company recently sold itself to a group of private equity investors for $12.3 billion. Because the Spanish broadcasting firm operates radio and television stations in an attractive corner of the media market, private equity investors have been aggressive with the debt they will issue to close the deal. Lenders will be asked for more than $8 billion to finance the transaction. These aggressive transactions will be accompanied by a slew of other large deals with equally hefty financing packages. All the companies will ask investors for financing all at the same time. As they compete for investor dollars in a touchy market, some mergers could struggle.