When China Oceanwide first agreed to buy US-based Genworth Financial, Barack Obama was still US president.
More than 1,400 days later, the $2.7bn (£2.1bn) deal has still not gone ahead, while the deadline has been extended 16 times.
In the meantime, Donald Trump became US president and relations between the US and China have soured considerably.
But the two companies are confident the deal will be signed, even though most takeovers take only six to 12 months.
The acquisition started in October 2016 during a spate of Chinese firms aggressively buying American assets.
"The Genworth saga is unique not only given the length of time that has elapsed since the two sides agreed to the deal, but also because of the twists and turns that have occurred along the way," said Mark Palmer, an analyst at investment firm BTIG.
Challenges that Genworth, an insurance firm, and Oceanwide, an investment company, have faced include gaining the approval of various regulators including those from several American states in which Genworth operates.
Another complicating factor is that many US-China deals need to be approved by the US Committee on Foreign Investment in the United States (CFIUS).
More recently there have been issues around China Oceanwide's efforts to secure financing for the deal, complicated by in-person discussions having to be delayed due to Covid-19 travel restrictions.
"We have overcome many hurdles during the past four years, demonstrating time and again our unwavering commitment to this transaction," said Lu Zhiqiang, chairman of Oceanwide.
Mergers and acquisitions (M&A) experts say a deal of this size should take a year on average.
But they can get complicated if either company is publicly-listed or strategically important for an economy.
Genworth Financial is a Fortune 500 company and listed on the New York Stock Exchange while China Oceanwide is a private firm with more than 10,000 employees globally.
"From my experience, any deal that takes longer than the average time has a low probability of success," said Jacob Doo, Chief Investment Officer at Envysion Wealth Management.
"As it is, the cost for more than 1,400 days is substantial and will continue to escalate, as I doubt that any approval will come before the US election."
The idea behind the deal was to give China Oceanwide a platform for global expansion and expertise it could bring back home.
This could now be a problem given the Trump administration's crackdown on Chinese firms doing business in the US.
"I recognize that this has been an extraordinarily long road to travel for our shareholders, regulators, employees and other stakeholders, and we greatly appreciate their patience," Tom McInerney, Genworth chief executive added.
Under the latest extension, Oceanwide has until the end of November to close the deal.