Charles Fain Lehman of the Washington Free Beacon reports on the potential impact of a new tax supported by multiple Democratic presidential candidates.

A financial transaction tax, though popular with 2020 Democrats, would raise little revenue and substantially shrink the U.S. economy, a recently released report concludes.

A transaction tax takes a percentage from financial trades, such as the sale or purchase of stocks, bonds, or derivatives. The United States levies an extremely small charge on each transaction to fund the Securities and Exchange Commission. A number of Democrats would like to bring a full-fledged financial transaction tax (FTT) back for the first time since 1965.

The idea’s most vocal proponent is presidential contender Sen. Bernie Sanders (I., Vt.) who has introduced a plan to charge a 0.5 percent fee on financial transactions. Sanders has made the tax “on Wall Street” a central revenue source to pay for his exorbitant spending proposals.

Sen. Elizabeth Warren (D., Mass.) introduced her own FTT proposal in 2015, Sen. Kamala Harris (D., Calif.) wants one to pay for expanding Medicare, and Mayor Pete Buttigieg has also said that he is “interested in” implementing an FTT. Congressional Democrats have supported the idea outside of the campaign trail. …

… These Democrats and others cite several justifications for an FTT. The tax is aimed at “Wall Street,” a preferred target of populist liberals—at least in principle, that means it also falls more heavily on those who hold a lot of wealth in investments. Additionally, such a tax would impose major restrictions on so-called high-frequency trading, which involves computer-run trades at fractions of a penny—profits that could be wiped out by the tax.