the most striking proposal is what IFC Media, the leading publishing house for the global wealth management industry, calls a “radical departure from normal taxation” — the taxing of unrealized gains for the ultra-rich.

An old investing adage is you don’t lose anything until you sell. Conversely, since unharvested returns are still unrealized gains, they’re not subject to taxation — at least not yet.

Her proposed 25% tax on unrealized gains for centi-millionaires with nine-figure fortunes or more would be a watershed moment for U.S. tax policy.