The FCC has adopted a Fourth Further Notice of Proposed Rulemaking proposing steps to prepare for an auction of the upper 37 GHz, 39 GHz, and 47 GHz bands. The 39 GHz band, combined with the Upper 37 GHz band, represents the largest amount of contiguous spectrum available for flexible-use wireless service in the millimeter wave bands. The FCC seeks comment on its proposal to transition existing spectrum holdings in the 39 GHz band to the new flexible-use band plan to promote efficient use by incumbents. Because the 39 GHz spectrum is currently licensed in small spectrum blocks and mismatched geographic areas, the FCC proposes to reconfigure the block size to 100 MHz to aid the transition from existing holdings to reconfigured holdings. Similarly, the FCC proposes to modify the Upper 37 GHz and 47 GHz band plans from 200 MHz to 100 MHz channels to auction all three bands at the same time. The FCC proposes a two phase incentive auction consisting of a phase where bidders bid on generic license blocks and a phase where winners can bid on specific frequencies. The FCC also proposes incentive payments and a pre-auction voucher exchange for incumbents to allow them to consolidate their holdings before the auction. For incumbents that choose not to participate in the auction, the FCC proposes mandatory repacking. Comments are due by September 17, 2018, and reply comments are due by October 8, 2018.