What Are Fungible Investments?

Definition and Example of a Fungible Investment

Fungibility is the ability to substitute one unit of a financial instrument for another unit of the same financial instrument. This works with paper money when you swap your dollar for someone else's. It doesn't work if you try to trade a U.S. dollar for a Canadian dollar—they don't share the same value.

In trading, fungibility implies the ability to buy or sell the same financial instrument in two or more different markets. A financial instrument (such as a stock, bond, or futures contract) is considered fungible if it can be bought or sold on one market or exchange, and then sold or bought on another market or exchange.

There are many fungible financial instruments, with the most popular being stocks listed on multiple exchanges, commodities (such as gold and silver), and currencies.

For example, if you can buy 100 shares of a stock on the Nasdaq in the U.S. and sell the same 100 shares of that stock on the London Stock Exchange in the U.K., with the net result being zero shares (100 bought and 100 sold), then the stock is fungible.

How a Fungible Investment Works

In simplest terms, fungible securities allow investors and speculators to buy low and sell high to make a profit. This works through a process known as "arbitrage." A trader takes advantage of a price difference in two different markets, buying at a lower price in one market and selling at a higher price in the other market.

For example, consider a stock that's listed on both the Austrian and German stock markets. One market has the shares trading at 6.23, and the other has them trading at 6.27 (both priced in euros). A trader can buy the shares at 6.23 on the one exchange and sell them at 6.27 on the other, netting 0.04 euro per share.

It becomes more complex when a stock or other asset is priced in different currencies on each exchange. For example, there can be more than 300 (the number fluctuates) listed on both the Canadian and U.S. stock markets.

The stocks on the Canadian market are listed in Canadian dollars, while the same stocks will be priced in U.S. dollars on the U.S. exchanges. Since stock prices constantly fluctuate, and so do exchange rates, fungible stocks are more likely to have arbitrage opportunities. Because of the exchange rates, though, spotting good opportunities requires more effort. 

What It Means for Individual Investors

Suppose you find a stock that trades on the U.S. exchange, currently with an ask price of $10 and a U.S. dollar (USD)/Canadian dollar (CAD) exchange rate of 1.30.

If the best deal you can get is a USD/CAD rate of 1.30, then it is expected that the stock would trade at about C$13 on the Canadian exchange. ($10 U.S. stock times 1.30 equals C$13.)

From second to second, there may be small discrepancies, as the currency rate changes and the stock is subject to its own price changes from buying and selling pressures. If traders see a large enough arbitrage opportunity to make a quick profit, they will step in. This pushes the underpriced market up (by buying) and the overpriced market down (by selling), bringing the two markets back into equilibrium.