NEW YORK — The Republican Party has taken a page straight out of the campaign books of Bernie Sanders and Elizabeth Warren. What? No, we're not kidding. In the party's 2016 platform, the GOP advocates for reinstating the Glass-Steagall Act, a Depression-era law that regulated the U.S. banking industry until it was repealed in 1999. Bringing the law back would lead to the breakup of major U.S. banks like JPMorgan Chase in order to separate investment banking from commercial banking.

Delegates fill the floor during the second day session of the Republican National Convention in Cleveland, Tuesday, July 19, 2016. (Photo: Associated Press/Matt Rourke) "It's a spectacular about-face by the Republican Party,'' said Aaron Klein, an economist and fellow at the Brookings Institution who has written about bank regulations. In a party that traditionally favours deregulation and hands-off governance, the adoption of this provision by the Republicans has raised eyebrows on Wall Street and among industry experts. Here's a primer about what Glass-Steagall is and what the GOP's adoption of this policy means: WHAT IS GLASS-STEAGALL? The Glass-Steagall Act of 1933 was passed in the wake of the stock market crash of 1929 and the thousands of banks failures that led up to the Great Depression. While the law did a lot of things, the provision most talked about was the law segregating the U.S. banking industry into commercial banks, or banks that take consumer deposits and operate branches, and investment banks, or those that trade and underwrite stocks and bonds and advise companies on making deals. It also separated out insurance. A bank could be only a commercial bank, an investment bank or an insurance company. That's it.

Democratic Presidential candidate Sen. Bernie Sanders, I-Vt., has been campaigning for a return of the Glass-Steagall Act, which would require the break-up of large U.S. banks. The Republican Party has now adopted that position. (Photo: The Associated Press/Jacquelyn Martin) WHY WAS IT REPEALED? As banks became larger and more complicated in the decades after the passage of Glass-Steagall, U.S. financial regulators had been easing their requirements under the law. Commercial banks increasingly started offering services that had traditionally been associated with investment banks. By the late 1990s, some historians and economists had begun to argue that Glass-Steagall was effectively dead. The final blow came when banking giant Citicorp said it intended to combine with Travelers, an insurance company. The proposed deal faced regulatory concerns from the get-go since Glass-Steagall prohibited the combination of insurance and banks. But a GOP-led Congress passed the Gramm-Leach-Bliley Act in 1999, which President Bill Clinton signed into law, which repealed that provision. Citicorp and Travelers became what's known as Citigroup. Other banks followed. Chase Manhattan Bank merged with JPMorgan & Co. to become JPMorgan Chase & Co. SO WHY BRING IT BACK? After the financial crisis, much anger was directed at Wall Street for the behaviour that led to the crisis. Part of that anger jelled into an argument that Glass-Steagall could have mitigated or prevented the financial crisis by keeping Wall Street from growing too large. While there had been pushes for the return of Glass-Steagall since its repeal, the appeal of that argument grew exponentially following the crisis. When advocates say they are in favour of restoring Glass-Steagall, they are typically not referring to the entire law, just the provision that would separate investment banks and commercial banks.