Should I hold any cash inside my investment portfolio?

For long-term growth money, generally no — cash earmarked for decades away just drags down returns, since stocks and bonds compound while cash barely keeps up with inflation. Your cash belongs elsewhere: a 3–6 month emergency fund in a high-yield savings account, plus any money you'll spend within the next 1–3 years, both kept entirely separate from your invested portfolio. The exception is retirees, who often hold 1–2 years of expenses in cash or T-bills so they can cover spending without selling stocks during a downturn — a buffer against sequence-of-returns risk. But trying to time the market by sitting in cash waiting for a dip usually backfires, because markets rise more often than they fall. Keep cash for its real jobs — emergencies and near-term spending — and let your long-horizon money stay fully invested. Size your reserve at wealthserene.com/tools/emergency-fund.