Bloomberg Opinion columnist Barry Ritholtz speaks with Sébastien Page, author of 2020's "Beyond Diversification: What Every Investor Needs to Know About Asset Allocation" and head of T. Rowe Price's multi-asset division, which manages $363.5 billion. Page is also a member of T. Rowe Price's asset allocation committee and management committee. He was previously an executive vice president at Pimco and a senior managing director at State Street Global Markets.