The Baillie Gifford-managed trust, which has delivered huge returns thanks to its backing for fast-growing technology stocks, rose almost 3% today and is back close to the record high seen before a fall back earlier in the year.
Its fortunes were lifted overnight by another landmark for the tech-heavy Nasdaq as Wall Street cheered full approval from US regulators for the Pfizer/BioNTech Covid-19 vaccine.
Scottish Mortgage, whose shares were up 29p to 1,381.5p today, benefited in particular from Elon Musk's Tesla lifting almost 4% and Amazon.com improving 2%.
The momentum continued in Asia as Chinese technology stocks rallied for a second day, with heavyweights Tencent and Alibaba up by around 9% after big losses in recent weeks fuelled by a regulatory crackdown.
Alibaba, the e-commerce giant co-founded by entrepreneur Jack Ma, accounts for 3.3% of the Scottish Mortgage portfolio, with Tencent 4.2% and Tesla 4.1%.
The vaccine approval from the US Food & Drug Administration boosted sentiment in the travel sector as British Airways owner IAG added 3.9p to 164.3p and Whitbread improved 73p to 3,118p.
The FTSE 100 index barely moved at just 0.77 points higher at 7109.84, as Sainsbury's shares gave up some of the 15.4% surge seen yesterday on the back of takeover speculation. The supermarket eased 6.1p to 333.9p.
The FTSE 250 index was down 10.4 points to 23,740.49, but there was fresh cheer for Marks & Spencer investors as favourable broker comment in the wake of Friday's surprise profits upgrade helped shares lift another 7.7p to 171.6p.