[jldugger]

> What's the limit - 30% 40%, 50%, 60%?

I'd wager at least 90 percent. Passive investing is generally designed to track active investor activity without effort, so it shouldn't add much inertia to the system. If Dave thinks IBM is overvalued and Under Armor is overvalued, the act of buying and selling will shift those numbers, and the index investors, instead of taking the opposite trade and undoing that flow of information, hold their portfolio.

IMO, the real challenge is active investors competing for access to that 10 percent of active invested money. There's no shortage of people happy to manage money under the 'heads I win, tails you lose' fee structure, and one hopes that the same people fighting over a smaller pool of cash would (more strongly than status quo) favor people who can actually produce results.