Oncor is Buffett's latest flop in dealmaking

Buffett's $9 billion bid to acquire Oncor Electric Delivery started to unravel last week after Paul Singer's Elliott Management Corp outmaneuvered the Oracle of Omaha by acquiring a small parcel of unsecured debt. That opened a window for Sempra Energy to swoop in and strike a deal to acquire the Texas utility.

The loss comes six months after another multibillion-dollar Buffett pursuit hit the skids.

In February, his Berkshire Hathaway committed $15 billion to help Kraft Heinz in a proposed buyout of Unilever. The AngloDutch consumer goods giant rejected the approach, and the offer was quickly pulled.

The collapse of two high-profile pursuits in such a short time frame is a rarity for Buffett, who has spent decades building Berkshire into a sprawling conglomerate through shrewd takeovers. While he's made many offers that went nowhere, it's less common for such losses to play out in public. Elliott's purchase from Fidelity Investments of $60 million worth of leveraged notes in Oncor's parent, Energy Future Intermediate Holding, was all it needed to do to block Buffett's bid, according to people familiar with the matter.