Christie's and Sotheby's reported combined full-year sales exceeding $9.2 billion for 2025, a figure that masks a structural shift underway in how ultra-high-net-worth individuals transact in art and collectibles. The headline number arrived courtesy of private treaty sales—off-auction deals brokered directly between buyers and sellers—and a handful of trophy lots that cleared eight- and nine-figure thresholds in evening sales across New York, Hong Kong, and London.

Public auction totals at both houses grew year-over-year, but the composition changed. Sotheby's reported a 12 percent increase in private sales volume, while Christie's noted that its private deals now represent roughly 30 percent of total turnover, up from 22 percent in 2023. Mid-tier lots—works and objects estimated between $500,000 and $2 million—saw softer sell-through rates, with buy-in percentages climbing into the high twenties at several marquee evening sales in the fourth quarter. The strength came from the poles: entry-level luxury goods under $100,000 and singular trophy pieces above $20 million.

This bifurcation matters because it signals where liquidity is concentrating. Family offices and sovereign wealth allocators are bypassing public auctions for discreet, negotiated purchases, a behavior that accelerated when capital gains tax discussions surfaced in multiple jurisdictions in mid-2024. Private sales carry lower transaction costs, no buyer's premium in some structures, and zero price discovery risk. When a Basquiat or a Patek Philippe reference 2497 changes hands off-market, comparables remain theoretical, and the next seller controls the narrative. The houses are responding by expanding private client teams and opening dedicated private-sale galleries in Geneva, Los Angeles, and Singapore.

Operators should watch for Q1 2026 consignment announcements, particularly whether estates and long-term collectors continue committing blue-chip works to public auction or pivot further toward private treaty. Sotheby's spring contemporary evening sale in May will be the first major test of whether the market can sustain $50 million+ hammer prices without the tailwind of 2025's liquidity surge. Christie's has already flagged a watch sale in Geneva for March that includes three $10 million+ estimates, a canary for whether private buyers are willing to compete publicly or prefer to wait for off-market approaches.

The $9.2 billion figure is a trailing indicator. The forward signal is in the private sales mix, now approaching one-third of total volume at the largest houses, and the widening gap between what sells at auction and what sells in silence.