Simple rule of thumb for determining asset allocation

"It is explained in a book: "The Missing Billionaires" by Victor Haghani and James White.

In practical terms, the book's crowning achievement is its explanation of the "Merton share". This is a simple rule of thumb for determining asset allocation, which says that allocations should rise in proportion to expected returns, fall in proportion to the investor's risk aversion and fall a lot in proportion to volatility (specifically, to its square)." [1]

1. "How to avoid a common investment mistake." The Economist, 21 Sept. 2023, p. NA.