What £20,000 Reveals About FTSE 100 Investment Returns

FTSE 100 investment returns over the past twelve months have been stronger than the index’s cautious reputation suggests, and a single stock illustrates just how wide the gap between passive and active outcomes can become. The UK blue-chip index has gained 19.1% in price terms over the last year, and with a trailing dividend yield of around 3.1%, the total return comes to 22.2%. A £20,000 stake placed a year ago in July 2025 would now be worth roughly £24,440.

FTSE 100 Investment Returns Versus Cash Over the Long Run

One year is a snapshot. The more instructive comparison stretches over decades. The average Stocks and Shares ISA has grown at a compound annual rate of 9.64% over the last decade, with dividends reinvested, against 1.21% a year for the average Cash ISA, according to advice site Unbiased. Over thirty years, the arithmetic is stark.

Nothing is guaranteed, and past rates rarely repeat with precision. But the compounding gap between equities and cash widens relentlessly over time. The cash saver ends up with less than a quarter of the equity investor’s pot on these figures.

The FTSE 100 also survived a sharp test in late February, when markets plunged after Donald Trump launched military action against Iran. The index had hit an all-time high of just over 10,910 on 27 February. The sell-off was acute; the recovery was quicker than most expected.

Computacenter: The FTSE 100’s Best-Performing Stock

For investors willing to move beyond index tracking, the last twelve months offered a more extreme example. Computacenter (LSE: CCC), the infrastructure services and technology sourcing group, rose 114% over the period, making it the top-performing stock in the FTSE 100. The company was promoted to the index in June 2026 alongside Aberdeen Group and Investec, replacing Berkeley Group, Mondi, and Rightmove, per the FTSE Russell June 2026 review. It was the first time in the company’s 44-year history that it had reached the FTSE 100, having been a member of the FTSE 250 since March 2009.

The FY 2025 final results show what drove that re-rating. Revenue reached £9,193.9m, up 32.0% (33.2% in constant currency), while adjusted operating profit came in at £274.7m, up 11.3% in constant currency from £246.7m in FY 2024. North America accounted for 39% of adjusted operating profit before central costs, up from 24% the previous year, with North American profits nearly doubling year on year. The AI infrastructure and data centre build-out in the US is the engine here.

The committed product order backlog at 31 December 2025 stood at £7.1bn, up 200.3% year on year in constant currency. That figure functions as a lead indicator: the work is contracted, the revenues are in the pipeline. At the end of FY 2024, the same backlog had already risen 116% year on year, so the acceleration in FY 2025 was a step-change rather than a continuation of a modest trend.

Computacenter ended 2025 with 215 major customers (defined as those generating over £1m of gross profit per annum), a net gain of 27 from 188 at end of FY 2024, the highest growth in five years. Adjusted diluted earnings per share were 175.1p, up 9.5%, and the total dividend per share rose 5.5% to 74.6p from 70.7p. The balance sheet carried adjusted net funds of £606.0m, up 25.7% from £482.2m. Early in 2026, the company completed the acquisition of AgreeYa for $120m, extending its professional services capability in North America and India.

The market value grew 44% to £4.2bn during 2026 ahead of the FTSE 100 promotion, according to Interactive Investor, with Q1 2026 performance beating expectations and the company upgrading its profit guidance on the back of hyperscale customer demand. Computacenter employs over 21,000 people and is described as the largest value-added reseller of information technology headquartered outside the United States.

The stock’s price-to-earnings ratio of 27 sits above the broader index average, reflecting a growth premium. Computacenter operates on tight margins and revenue is exposed to the pace of enterprise IT spending. If AI capital expenditure cycles down sooner than the order backlog implies, the re-rating would look stretched in retrospect. The FY 2024 results were a reminder of that fragility: adjusted profit before tax fell 8.6% that year before the cycle turned sharply.

For investors considering FTSE 100 investment returns over the next twelve months, the key test is whether North American hyperscale and data centre demand holds at the pace the order backlog implies. If it does, the earnings multiple looks reasonable. If enterprise spending pauses, the premium will compress quickly. The £7.1bn backlog is the number to watch.