In response to the recent yield curve inversion, Allianz chief economic adviser Mohamed El-Erian warned that negative yields in the U.S. could wreak as much havoc as political upheaval. This according to a recent article in Chief Investment Officer.

The article reports that El-Erian has been alarmed by the decline in Treasury yields and explains, “Negative rates are a reality in Europe and Japan, and some say they have held back economic advances in those places. Savers have been hurt and banks have had a tough time generating profits.”

Earlier this month, El-Erian reportedly commented in an interview with Yahoo Finance, “I’m going to be really worried because negative yields in the US, the world’s biggest financial market, will break things. The system is not built to operate with negative yields.” But the article reports that former Fed chairman Alan Greenspan told Bloomberg that as bond yields fall, there will be “no barrier to Treasury yields going below zero.”

According to El-Erian, the article says, U.S. financial institutions are not set up to handle negative rates, adding, “banks, retirement plans, and life insurers all depend on positive rates.” He asserted that the ECB “made that mistake and they can’t get out of it,” adding, “And the Fed has to be careful not to make the same mistake.”