The Financial Post reports in its Friday edition that copper's bull run is losing momentum, a troubling sign for economic growth and investors who bet demand related to the shift to electric vehicles would offset a supply glut. The Post's Gabriel Friedman writes that the price of the metal briefly dropped below $4 (U.S.) a pound this week, an important psychological threshold. Copper is considered a gauge of economic health because it is a key input in a broad range of big-ticket items such as infrastructure projects and many consumer goods. The shift in sentiment about the economic outlook is now testing expectations that the longer-term demand for copper will offset the disinflationary effect of forecasts that predict surplus production in 2023 and 2024. Copper appears to be entering a period of volatility. In March, 2020, it started a bull run, surging 125 per cent to $4.94 (U.S.) a pound and is now down 18 per cent. The trend is hammering Canadian-listed copper producers. Teck Resources dropped 9.2 per cent to $40.23 per share on Thursday, Ivanhoe fell 5.4 per cent to $7.18 and Hudbay Minerals declined 9.2 per cent to $5.24. The Post warns that the copper surplus is expected to grow as new mines come on-line.