Scenario Analysis (or Stress Testing) forces a portfolio to survive a specific hypothetical or historical Black Swan event.
Unlike a general backtest, a Stress Test isolates extreme events—like the 2008 Financial Crisis, the 2020 COVID Crash, or the 1970s Stagflation—and applies those exact market conditions to your current holdings.
This answers a critical risk management question: 'If the exact conditions of the Dotcom Bubble were to happen tomorrow, what would my portfolio look like?' It is an essential tool for ensuring an investor's psychological risk tolerance aligns with their portfolio's construction.