THE £15 billion Scottish Mortgage Investment Trust yesterday emphasised long-run stock market returns are driven by a “small number of exceptional companies”.

Flagging its stake in Californian electric vehicle, battery systems and solar power group Tesla, the trust said: “The increase in Tesla’s stock price and its dramatic impact on the trust’s returns should be seen in context. Whilst [Tesla] and its colourful founder attract an unusually high degree of attention, emotion and noise, the underlying return picture is far from an aberration.

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“Returns are concentrated in a handful of big winners. With far less drama, this has been the case for our holdings in both Amazon and Tencent over the past decade. Tesla’s success has been earned over a period of ownership extending back to 2013 and, as with most successful investments, we have endured large drawdowns in its stock price on the way to the current position.”

The trust’s net asset value per share rose 76% in the six months to September 30 in total return terms, compared with a corresponding 24% increase in the FTSE All-World index.

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Scottish Mortgage said: “Six months of data is too short a period to infer much that is useful from stock prices.”

NAV per share with debt at fair value has over five years risen 340% against a 96% gain in the FTSE All-World index, both in total return terms. Over 10 years, NAV has increased by 674%, against a 191% gain for the index.

Scottish Mortgage declared an interim dividend of 1.45p per share, noting this was a “modest increase” on the corresponding payout of 1.39p for the same period of last year.