risk
Diversification, the only free lunch
The rule
Mixing holdings pushed by truly different forces can lower risk without giving up return. It is the one free lunch in investing, but only within limits.
Where it flips
Diversification is a free lunch within limits, not a shield against everything. In a broad crash, most assets fall together. Past a point, adding more holdings only adds cost and clutter. It cuts single-story risk, not market-wide risk.
Markowitz showed with maths that what matters is not each holding alone but how they move together. Assets driven by different forces partly cancel each other out, so a sensible mix can carry less risk for the same expected return. That cancelling benefit, which no single holding gives, is the closest thing markets offer to a free lunch. The limit is that it only works when the forces are truly different. Owning twelve Indian share funds that all rise and fall together is variety on paper, not real risk variety. Adding a debt part, a little gold, or an international index brings truly different forces and so truly different risk. Count the underlying forces, not the number of folios in the account.
A worked example
A portfolio of twelve funds looks well spread, yet after looking through the wrappers, 78% still depends on Indian large-cap shares. A plainer mix of broad shares, short-term debt, and a small gold part carries fewer identical forces. [illustrative]
How to spot it
- ·you count the underlying forces, not the number of wrappers
- ·you check fund overlap and shared sectors before feeling well spread
- ·each part can name a force the others do not carry
Harry Markowitz · Portfolio Selection