If the city allowed MBM bidding, it was likely that the interest rates would be nonascending.
It should be no surprise, therefore, that several large Wall Street underwriters gave Pittsburgh officials early indications that they would not bid for the city's bonds or "support" its issue in the secondary market if the city allowed MBM bidding.
There was a concern that MBM bidding could result in "yield curve inversions"; in other words, non-ascending interest rates.
This becomes possible with MBM bidding since, generally, institutional investors can afford to purchase selected maturities but not an entire issue.
Of the various bidding formats available, finance staff had decided to recommend only one innovation to him, the MBM bidding format; but he suggested (over the objections of his staff) utilizing all the other innovations available to the city, including the open auction format which reveals both the names of the bidders and their bids.
One of the concerns about MBM bidding was the possibility that there might be several winning bidders and, consequently, several payments by wire on the date of settlement.