The Samsung Galaxy S5 reportedly disappointed its maker in terms of sales, performing 40 percent poorer than expected in its first three months on the market.

Considered one of the hottest handsets of this year, the Samsung Galaxy S5 made its debut back in early September as the company's flagship smartphone for 2014. Despite its high-end specs and features, however, it appears that the device did not sell as well as expected.

According to a new report from The Wall Street Journal (WSJ), the Galaxy S5 has so far performed below the company's expectations. Samsung reportedly sold 12 million Galaxy S5 units in the handset's three months on sale, i.e. 4 million fewer units compared to the Galaxy S4's performance in the same timeframe since its debut. At the same time, these 12 million Galaxy S5 units sold represent 40 percent less than the company had projected.

Galaxy S5 sales were reportedly down over 50 percent in China, which is a major market. In fact, the only major market where sales actually increased was the U.S., which is Samsung's biggest market.

The report further notes that Samsung overestimated demand and created excess supply, which in turn led to an increase in advertising costs in order to get rid of units that were simply "piling up in warehouses."

This is not to say that the Samsung Galaxy S5 is a failure, but the smartphone is not as successful as the company expected - at least not yet. Samsung saw a weak quarter overall, with sluggish profits and revenue.

In light of its recent performance, the company recently decided to revise its mobile strategy for next year and dramatically reduce the number of handsets it will offer in 2015. It remains to be seen whether that strategy will prove to be successful and boost sales of its flagship devices.

The WSJ also cites sources who indicate that Samsung is looking into making some changes at the executive level, but nothing is confirmed at this point. Such plans are reportedly far from final and it's tough to tell at this point whether they will actually materialize.

Samsung has offered no comment so far regarding the success of its Galaxy S5 smartphone, or its plans to shake up its strategies.