If I had to guess it would be something to do with this part:
"Solow, auction experts said, had a history of not seeking guarantees, choosing to negotiate for a portion of the buyer’s fees instead. Last night that strategy proved fateful."
The vendor and the auctioneer have some private agreement, which meant the sale probably ended below an acceptable price.
So what seems to have happened here is that the seller set a de facto minimum of $70M before their deal with Sothebys would take effect, and, seeing that there was no interest, pulled the sale.
More details here: $70 Million Giacometti Flops at Sotheby’s, as Demand for Trophy Art Softens
https://news.artnet.com/market/70-million-giacometti-flops-a...
The auctioneer will not specifically identify bids placed on behalf of the seller. The auctioneer may further bid on behalf of the seller, up to the amount of the reserve, by placing successive or consecutive bids for a lot or by placing bids in response to other bidders.
Of course people close to the process know which part of it is a game.
"We disclosed our nonsense in the terms and conditions, it's your fault if you don't catch on" is a fine way to do business if that is how you want to be seen doing business.
When items like this go up for auction, sellers often set a "minimum" price. If that isn't met, the item isn't sold and remains the property of the original owner.
As you've highlighted, the reserve price doesn't have to be guaranteed by the auction house. So if this price isn't met, nobody gets the item (unlike the standard which is that the auction house will buy the item for the reserve price).
The 50% is probably the guy rounding the estimate to make a point.
As for why 64.25 wasn't enough but 70 would have been, I don't know. My understanding is that a lot of pieces sell for above their high estimate, so I'd guess that the seller was expecting/hoping for that? I do also think that 35% versus 40% matters a lot more when that difference is 6 million dollars in absolute terms.
"...carried a pre-sale estimate of over $70 million..."
"...the artwork came to the market without a minimum price guarantee from the auction house..."
"Oliver Barker, the evening’s auctioneer, began the bidding for the bust at $59 million. But his bids stalled at $64.25 million. Three minutes passed as he hunched low over the rostrum, hunting for bidders, Nosferatu-like, until announcing that the lot was a pass."
Can someone explain how these things relate? If the pre-sale estimate was $70m, there was no minimum price guarantee (a reserve?) and a bid of $64.25 million (90% of the estimate) why didn't it sell?
The article goes on to say:
"“No one who is an informed buyer who is serious in this market — billionaire or not — is going to pay what essentially amounts to a 50 percent premium on something that sold in recent memory,” said Todd Levin, an adviser in New York."
Someone was willing to pay $64.25 million, a 30% premium on the last sale, $70 million is only 40%. Where does 50% come from? Why is $64.25 million bad but $70 million is good.