On Thursday it was "The Most Important New Development in Years". Two days later it was history.
Investors had been just starting to get their tongues around the name of Pfizer's promising new heart disease medicine, Torcetrapib, which formed the centrepiece of the drug maker's presentations at a research and development conference at its giant lab complex in Connecticut last week.
Pfizer grew to become the biggest pharmaceuticals company in the world on the back of its blockbuster cholesterol medicine Lipitor, the first to lower LDL, so-called "bad cholesterol", whose build-up increases the risk of heart disease.
Torcetrapib was to be its next trick, a drug designed to raise HDL, "good cholesterol", which improves people's cardiovascular health.
But data revealed to Pfizer on Saturday, by the trial's independent monitors, changed everything.
Far from reducing patients' risk of heart problems, the drug appeared to be causing more of them to die of heart attacks and other complications of high blood pressure. The monitors told Pfizer to halt the trial.
Executives abandoned their weekend plans - Pfizer's chief executive, Jeffrey Kindler, had to skip his daughter's 18th birthday party - and met to discuss the future for Torcetrapib.
The inescapable conclusion: no future.
After US$800 million ($1.2 billion) spent on the drug, the project has been scrapped. And with it goes the main plank of Pfizer's strategy for replacing annual revenues of US$13 billon from Lipitor, which loses patent protection in the US in 2010.
The share price reaction was savage, down 15 per cent at the opening of trading. By the close, the shares had recovered slightly but were still down US$2.96 (11 per cent) at US$24.90, wiping US$21.3 billion off the company's value.
So far, so predictable. What happens next, though, will have consequences not just for Pfizer and its chances of hanging on to the top spot in the pharmaceuticals food chain. The company now looks set to embark on a more dramatic cost-cutting drive, and perhaps also an acquisition spree, that could reshape the entire drug industry.
The drug was being trialled on 1300 Australians at 25 clinics nationwide. It is understood no New Zealanders were involved with the trial.