tax stock transactions at 0.5 percent. It will raise money from a group who can afford it and discourage the speculators

Purchases of stocks, bonds and other financial instruments in the United States are not taxed - they just pay a tiny fee (less than a penny). Other countries tax stock transactions.
It would mostly hurt short-term “day traders”, thereby discouraging speculation.Less speculation could lead to more stability, encouraging serious, long-term investors. A sales tax on Wall Street of 0.5 percent could raise up to $175 billion a year, even if the total number of transactions drops by 50%.