The company behind the addictive app "Candy Crush Saga" saw a 15 percent fall in shares during its trading debut on Wednesday.

King Digital Entertainment Plc, which brought in around $500 million in its initial public offering, was valued at about $6 billion, Reuters reported.

Launched about two years ago, Candy Crush is a free app that boasts almost 100 million users and garners money when people pay for extra levels and features. It has been downloaded onto mobile devices more than 500 million times since its debut.

The popular game brings in around 75 percent of King's profits even though the developer has around 180 other games, according to Reuters.

On Wednesday, King's trading debut saw shares open at $20.50 and drop to a low of $19.08 on the New York Stock Exchange. Of the 22.2 million shares offered, King sold 15.5 million.

King had priced the IPO at the midpoint of the stock's expected range, Forbes reported. JP Morgan, Credit Suisse and Bank of America Merrill Lynch were lead book-running managers for King's IPO, according to Forbes.

The company's IPO has been compared to Zynga Inc, which went public in 2011 and was valued at $7 billion. The mobile gaming company best known for making "Farmville" has since seen its market value drop to $4.2 billion.

Zynga's diminishing market value has "raised concerns about the danger of investing in companies that rely heavily on a single hit game," according to Reuters.

In an irony of the quickly changing popular app world, Candy Crush was the game that edged out Farmville as Facebook's No. 1 app, Forbes reported.

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