<p>The theft of Renoir paintings with unresolved Nazi-era histories has brought the art market’s twin vulnerabilities—physical security and incomplete provenance—into sharp focus. As UK auction-data s
<p>From a restituted Kandinsky headed for a $30 million sale to a museum jewel heist and a disputed Haring drawing, the market’s most consequential risks continue to trace back to what can—and cannot—
