"Crew members and executives will see a 12.0% increase in their dividend, to $185.44 from $165.57 for 2015," under Vanguard Group's Partnership Plan, writes Independent Adviser for Vanguard Investors publisher Daniel Wiener in a report to clients, citing sources at the Malvern mutual fund giant.

Senior managers get most of their compensation from bonuses; hourly employees are mostly excluded. The increase was similar to last year's, though Vanguard growth was down with the markets in 2015, Wiener noted. Last year veterans also got a special 40th anniversary bonus.

As a private for-profit company, Vanguard doesn't disclose executive pay. Using old estimates from when Vanguard did make its pay public more than 20 years ago, Wiener estimates top managers would earn in the tens of millions of dollars a year: "It may not be hedge fund money, but it isn’t seaman’s wages either."

Plan pay has steadily increased faster than the S&P 500 Index in Vanguard's most popular funds, Wiener noted.