The FCC's midband CBRS spectrum auction topped $500 million Tuesday (July 28) after round-six bidding that pushed the total up by over $60 million to $519,155,888. 

Related: FCC Launches First 5G Mid-Band Auction 

The auction, the FCC's first-ever flexible-license mid-band auction, began with a single, six-hour, round; moved to two, two-hour rounds, for the succeeding two days, and on Wednesday (July 29), will shift to three, hour-and-a-half rounds until further notice, which is at least through Thursday, according to the FCC's web site. 

The FCC is auctioning 70 MHz worth of county-based Priority Access Licenses (PALs) (a whopping 22,631 of them) in the 3550-3650 MHz 93.5 GHz) band. It is the most-ever flexible-use licenses available in a single auction, the FCC said. Each license will be a 10 MHz unpaired channel. There are 271 qualified bidders. 

The band is being shared by federal and non-federal users, with incumbents--Navy radar, for example--having the top priority, followed by PALs and then general authorized users (GAAs).  

Sasha Javid, COO of BitPath and former top FCC auction official, says that a couple of the key questions the auction should answer is how much Verizon, AT&T and T-Mobile/Sprint is willing to pay for spectrum that requires frequency coordination and "strict" power limits and whether Charter and Comcast (or Dish) will "take the plunge" and bid "in a meaningful way."