M&A Accounting rules changed dramatically in 2001 under FAS 141 and FAS 142. EG8NB8T4PTHQ
In addition to the elimination of pooling, goodwill would no longer be amortized for book purposes. In 2009, an important revision to the 2001 changes became effective, among other things changing the way investment banking fees, minority (noncontrolling) interests, negative goodwill, and in-process R&D are accounted for.
I still see lots of merger and LBO models incorporating out of date accounting practices. To learn how to build a full merger model, check out our Premium Package self-study program.