On the sidelines of the annual shareholders meeting of his Berkshire Hathaway empire in Omaha, Buffett made a surprise appearance at a gathering called Variant Perspectives, organized by a group of women financial professionals aiming to end the imbalance.
"We'll miss a lot in the future, we missed a lot in the past", Buffett said, referring to investing opportunities.
By that measure, Berkshire reported operating earnings of $5.56 billion, or $3,387.56 per Class A share.
Mr Buffett defended 3G's management, saying the combined company is doing well operationally and its current problems can not be blamed on a lack of investment.
Analysts on average expected operating profit of about $3,399 per Class A share, according to Refinitiv data.More news: Samsung Announces New 64MP ISOCELL Camera Sensor for Smartphones
More news: Rugby lifeline for Israel Folau ... in Asia?
More news: US Treasury will not hand over Trump tax returns to Congress
But his acquisition of 26.7 per cent stake in food giant Kraft Heinz still gave the investment giant cause for concern, having not yet filed its quarterly results.
One of the major investments by Berkshire, Kraft Heinz was created by a merge of Kraft Foods and H.J. Heinz in 2015.
He said 3G had more willingness to take on leverage and "pay up", but in many cases also had "way better operators".
BNSF's profit rose 9 percent to US$1.25 billion as higher demand from the energy and industrial sectors offset lower volumes attributed to severe winter weather and flooding.
Berkshire's Class A shares closed Friday at US$327,765.61, and its Class B shares closed at US$218.60.