Answer:
Because the stock market is usually irrational.
Explanation:
The stock market is a minor indicator of the health of the economy "because the stock market is usually irrational."
Given that before the stock market crashes, there is usually the placement of high value on stocks, which makes it irrational thereby making it difficult to anticipate the stock market crash.
Hence, it does not serve as the main indicator of the health of the economy.
