Reps made inappropriate sales pitches to business customers about the tax benefits of using AmEx's wire payment services.
Facebook recorded a full-year "windfall" of $934 million from a a change in the way companies account for stock payments to employees.
Some changes in 2016 have altered the picture somewhat for small and midsize companies.
Critics complain that the Treasury's assault on corporate tax shelters amounts to overkill. The tax man says he's misunderstood.
"Partial liquidation" doesn't sound so bad to shareholders who have enjoyed the tax benefits.
