Sony’s stock has been knocked down to ‘junk’ status by Moody’s Investors Service after other areas of the firm’s business continue to struggle.

It follows confirmation that Sony sold-through 4.2 million PS4 units since launch.

Now, GI.biz reports that Moody’s has cut Sony’s stock rating from Baa3 to Ba1, which the site confirms is one notch below investment grade, meaning that potential investors should be dissuaded from putting money into the business. The firm still lists Sony’s status as “stable,” however.

A statement from the firm reads, “While Sony has made progress in its restructuring and benefits from continued profitability in several of its business segments, it still faces challenges to improve and stabilize its overall profitability and, in the near term, to achieve a profile that Moody’s views as consistent with an investment grade rating.

“Of primary concern are the challenges facing the company’s TV and PC businesses, both of which face intense global competition, rapid changes in technology, and product obsolescence. Sony’s profitability is likely to remain weak and volatile, as we expect the majority of its core consumer electronics businesses – such as TVs, mobile, digital cameras and personal computers – to continue to face significant downward earnings pressure.”

In games, Moody’s conceded that Sony’s game business could see a profit increase, but, “not to the extent seen with the profitability level in 2010.”

What do you make of Sony’s business beyond games? Let us know below.