Had the offer been accepted it would have smashed United's current £30m record paid for Dimitar Berbatov in 2008, and equaled the £38m paid by Manchester City for Sergio Aguero last summer .
But the approach failed once the Santos star made it clear he wanted to fulfil his promise to stay in Brazil until after the 2014 World Cup on home soil.
Reports suggest Ferguson turned his attentions to Neymar after losing out to Paris St Germain in the race to sign fellow Brazil ace Lucas Moura.
The Red Devils had tabled a £32m bid for the 19-year-old Olympic silver-medallist earlier this summer, but the teenager opted for PSG instead, leading Ferguson to explore other options.
Neymar has bagged 113 goals in 190 games for Santos, and has attracted interest from Chelsea, Manchester City, Barcelona and Real Madrid in the past.
At this summer's London Olympics, the 20-year-old was expected to fire his country to their first ever Olympic gold medal, but came up short in the final, as Brazil lost 2-1 to Mexico.
But that hasn't affected his rocketing profile, and the forward remains one of football's hottest properties.
A move to one of Europe's big leagues is surely only a matter of time, and there would be no shortage of suitors should Santos decide to sell.
Reports of United's deadline day bid will spark questions over the future of Wayne Rooney. The England striker is currently sidelined through injury, but recent £24m acquisition Robin van Persie has settled quickly in Manchester, and the addition of Neymar would further crowd out the United man.
But Santos board member Felipe Faro has since insisted that Manchester United did not make a deadline day bid for the Brazil striker, contrary to reports in the British press.
United were active in the transfer market this summer, spending close to £50m on Robin van Persie, Shinji Kagawa and Alexander Buttner, but the addition of Neymar would have almost doubled their spending, and eclipsed even Chelsea's purchase of Eden Hazard for £32m.