Moody's Corporation Investor Services upgraded Apple Inc's long-term credit rating to Aaa, making it one of the three highest-rated US companies in the S & P APP, along with Microsoft Corp (MSFT.US) and Johnson & Johnson (JNJ.US), Zhitong Financial APP learned.

"the upgrade of Apple Inc to Aaa reflects the company's excellent liquidity, strong earnings growth over the next two to three years and very strong business performance," Raj Joshi, an analyst at Moody's Corporation, said in a statement on Tuesday.

Moody's Corporation said Apple Inc's financial policy of transitioning to a net cash-neutral position and its capital allocation since the US tax reform meant the company would "maintain an unusually strong liquidity position over the next three to five years".

It is reported that Apple Inc has become the world's largest company by market capitalization, driven by the success of iPhone and its foray into lucrative new markets. Apple Inc's market capitalization hovers around $3,000bn this year, and investors believe the company's expansion into augmented reality (AR) and cars could help keep its performance growing.

In addition, since 2012, the company has been paying dividends and stock buybacks. As of October, the company had $191 billion in cash and marketable securities. In 2018, the company told investors it was trying to be cash-neutral. As of October, Apple Inc had $125 billion in debt, including floating-rate and fixed-rate bonds. This brings its net cash position to $66 billion. According to the company, it returned $24 billion to shareholders in the last quarter.