Kraft Heinz's proposed merger with Unilever marks another consolidation effort in the food industry by Warren Buffett's Berkshire Hathaway and Brazilian private-equity firm 3G Capital.
A more than $140 billion tie-up between Unilever and Kraft Heinz would be the biggest U.S. acquisition of a foreign company and the largest in the consumer staples sector, said Richard Peterson, senior director at S&P Global Market Intelligence. From a global perspective, the proposed merger would be the fourth-largest on record, he said.
"3G and Berkshire, they're noted for trying to find efficiencies, and this is on a massive scale," Peterson said.
The two investor groups together own just over half of Kraft Heinz. As of December, Berkshire had a 26.7 percent stake in the food company's outstanding shares and 3G owned 23.9 percent, according to S&P.
Spokespeople for the Buffett-led conglomerate and 3G did not immediately respond to a CNBC request for comment.
Hellmann's mayonnaise owner Unilever rejected Kraft Heinz's offer Friday, saying the proposal "fundamentally undervalues" the Anglo-Dutch consumer goods giant. Kraft Heinz said in a statement that it still looks forward to reaching an agreement on a deal, but added that it's uncertain whether another offer will be made.