Shares of several bitcoin (BTC)-related companies have seen a significant rise, amid the digital currency's appreciation to its highest in 18 months.

Among them, the shares of cryptocurrency exchange Coinbase (COIN) stand out, for registering a 79% increase in the last two months. Similarly, both bitcoin mining firm Cleanspark (CLSK) and digital asset investment manager Galaxy (GLXY. TO) rose 72%.

In addition to the shares of companies in the industry, other traditional instruments of exposure to the digital currency also went higher. For example, Grayscale's bitcoin investment fund "GBTC" is up 74%.

Matrixport explained that this happens because, as the bitcoin bull market expands, traditional investors buy regulated instruments from their industry. This way, they can gain upside exposure.

According to Matrixport, the performance of industry stocks shows pent-up demand from traditional investors seeking exposure to BTC. At the same time, he argues that it reflects that they need a U.S.-listed bitcoin spot ETF as an alternative.