Should my emergency fund ever be invested in the stock market?

Generally no — at least not the core of it. The whole point of an emergency fund is that the money is there, in full, exactly when a crisis hits, and emergencies often coincide with bad markets (a recession causes both job losses and stock declines). If your fund is in stocks, you could be forced to sell at a 20–30% loss precisely when you need cash. Keep your first 3–6 months in liquid, insured savings. Some people who already have a robust cushion choose to hold a deeper, secondary layer in slightly higher-yielding but still-safe places like T-bills, money market funds, or I-bonds — not equities. If you're tempted to invest the reserve to fight inflation, use safe yield instead and keep your long-term investing money separate. Size the safe core first at wealthserene.com/tools/emergency-fund.