Friday brought a solid rebound to the stock market, which has seen an uptick in volatility. With the market at the one-year anniversary of the beginning of the coronavirus bear market, it's easy to understand why some investors have been on edge.

But that wasn't evident from today's market action, with major stock indexes all climbing. As of noon EST, the Dow Jones Industrial Average (DJINDICES:^DJI) was up 122 points to 31,615. The S&P 500 (SNPINDEX:^GSPC) rose 9 points to 3,923, and the Nasdaq Composite (NASDAQINDEX:^IXIC) moved higher by 82 points to 13,948.

Many investors have been focused on high-growth stocks in areas like cloud computing, cryptocurrency, and electric vehicles. Yet as the broader economy starts to see some signs of life, officials at the U.S. Treasury are making arguments for why reflationary trends might start to assert themselves in the near future. As you'll see below, that's pushing two long-neglected stocks higher today.

Yellen weighs in on the economy

Janet Yellen was formerly chair of the Federal Reserve, but she's recently moved into her new role heading up the Treasury Department for the Biden administration. From that standpoint, Yellen has a different mission, trying to prompt economic growth as the world emerges from the worst of the COVID-19 pandemic.

As Fed chair, Yellen was vocal about the need for the federal government to support fiscal policies that would complement the central bank's monetary efforts to bolster economic growth. Now, she is more directly pointing to the complete lack of inflation over the past decade and arguing that it's time to pull out all the stops on both the fiscal and monetary side. With high levels of unemployment and the financial damage that the pandemic has caused, the Treasury chief sees a greater risk from failing to take enough action to help people.

Those comments are having an impact on financial markets. The 30-year Treasury bond yield recently moved above 2% for the first time since before the pandemic. It also led some investors to look at what's commonly seen as a bellwether for economic activity: copper.

Three spools of copper wire on a shelf.

Image source: Getty Images.

All that glitters is...copper?

Copper prices moved above $4 per pound on Friday. That might not sound like a big deal, but it was the first time in nearly a decade that the base metal had risen to such heights.

That move was good news for major copper producers. Freeport-McMoRan (NYSE:FCX), which operates the largest copper mine in the world, saw a 7% rise in its stock. Southern Copper (NYSE:SCCO) climbed 5%, hitting an all-time high as the share price has more than tripled in just the past year.

Copper performs well in economic expansions because of its industrial uses. You'll find the metal in wiring, piping, and plumbing for residential and commercial construction projects. Household appliances also use a substantial amount of the metal.

Moreover, more cutting-edge technologies also make use of copper. Its high conductivity makes it a valuable material for use in wind turbines and in connecting renewable energy generation equipment to electrical power grids. Many electric vehicles use considerable amounts of copper.

If the economy does continue to gain ground, then copper could sustain its recent rise. That would be good news not just for investors in Freeport and Southern Copper, but potentially for the entire industrial sector as well.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.