When investors and the public think of Warren Buffett, chances are high that they think of his company or Mr. Buffett very positively. Berkshire Hathaway Inc. (NYSE: BRK-A) has become one of the most powerful companies in the world in recent years.

After having moved from being considered an insurance holding company to a truly diversified conglomerate at S&P, now Buffett’s empire has expanded handily with the acquisitions of Precision Castparts ($37 billion) and BNSF ($26 billion) in rail.

With all of the hoopla about Buffett, most investors might just assume that Berkshire Hathaway has a full on AAA rating. Not so. In fact, it is down at A+, according to Fitch — with the possibility of a credit pressure ahead.

Fitch Ratings assigned A+ ratings to seven new traunches of senior notes issued by Berkshire Hathaway and by its wholly owned finance subsidiary Berkshire Hathaway Finance Corporation. The total offering was right at $9 billion.

It turns out that $5.5 billion of the notes are senior unsecured notes issued by Berkshire Hathaway itself, with the other $3.5 billion of senior notes having been issued by the Berkshire Hathaway Finance Corporation subsidiary, which were said to be fully and unconditionally guaranteed by the parent.

24/7 Wall St actively follows the moves of Buffett and Berkshire Hathaway. On top of the new changes for Buffett’s 2016 top stock holdings, here are several issues to consider of late (with links to more detail):

• Buffett Still Grew Income and Book Value in 2015
• Buffett Comes Clean on Kinder Morgan Stake
• Why Buffett Openly Loves Large Stock Buybacks

Berkshire Hathaway was using these funds to repay a $10 billion bank loan that was part of the $37.2 billion purchase price for Precision Castparts. The company also was using part of the proceeds to refinance $300 million of 2.2% senior notes that matured and were repaid on February 11, 2016.

As far as why the offering was given an A+ rating, Fitch Ratings credit report said:

Berkshire Hathaway’s consolidated financial leverage ratio remained under 30% after the $9 billion debt issuance and the assumptions of $5 billion in Precision Castparts debt obligations. This level of financial leverage would not trigger any rating sensitivities, however, Berkshire Hathaway is approaching Fitch’s limits on financial leverage and interest coverage. Consequently, another material acquisition funded with significant amounts of debt would place downward pressure on Berkshire Hathaway ratings.