10 hottest ISA shares, funds and trusts: week ended 19 September 2025

We look at the investments ii customers have been buying within their ISAs during the previous week. The data includes only real-time trades, not regular investing instructions, and combines the use of both existing funds and new money.

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Top 10 shares in ISAs

Despite its meteoric rise over the past few years from 70p to over 1,100p, there’s still heavy demand for Rolls-Royce Holdings (LSE:RR.) shares as the positive news flow continues.

A rise of six places puts the engineer at the top of the table of most-bought stock in ISAs on the ii platform for the first time in over a month. Investors have been encouraged by a deal between the UK and US that will speed up approvals for projects such as Rolls-Royce’s small modular reactor.

There was further optimism when Goldman Sachs initiated coverage of Rolls-Royce with a “buy” rating and price target of 1,290p. The broker’s analysis reflects a “compelling operational turnaround” and positive themes including the engine aftermarket at a time when travel demand is outstripping supply.

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Enthusiasm for last week’s number one subsided, leaving Phoenix Group Holdings (LSE:PHNX) down six places in seventh position.

Among the new entries this week is Renalytix (LSE:RENX), in at number three following a collaboration agreement with Tempus AI Inc Class A common stock (NASDAQ:TEM). The tie-up will make the company’s kidneyintelX.dkd prognostic blood testing - the only Food and Drug Administration-approved and Medicare reimbursed prognostic test to support early stage risk assessment in chronic kidney disease - more widely available for patients in the US. 

Shares in the AIM-listed company doubled following the news, and even after announcing a £4 million fundraising at 9.5p, the business is still valued at over £30 million.

Hemogenyx Pharmaceuticals (LSE:HEMO) is new at number eight after its shares continued their ascent to an 18-month high. The rally came as the company announced that a third patient had been successfully treated in the ongoing Phase I clinical trial of HG-CT-1 as a treatment for acute myeloid leukemia in adults.

“These results reinforce the promise of HG-CT-1 as a potential new therapy for one of the most aggressive and intractable forms of leukemia,” said CEO and co-founder Dr Vladislav Sandler.

When I first covered Hemogenyxhere a couple of weeks ago, the shares had risen from 180p to over 990p. Last week they peaked at over 1,700p, valuing the business at over £90 million.

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An impressive recovery since the early August annual results has completely unwound, with Diageo (LSE:DGE) shares back at a key technical support level around 1,800p. Investors perhaps see Diageo as cheap again and at a price where further support could appear. The decline comes despite the appointment of highly regarded former Rolls-Royce boss John Rishton as a non-executive director.

Top 10 funds and trusts in ISAs

Royal London Short Term Money Market and Artemis Global Income remain unchanged in the top two slots for the fifth consecutive week.

The Royal London fund offers a “cash-like return”, with its yield closely linked to the Bank of England’s base rate. As well as low-risk income, the Royal London fund can be seen as a place to park cash while awaiting new opportunities.

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Artemis Global Income is a value-focused fund. As we explain in a recent analysis article, value investing has experienced a renaissance after more than a decade in the wilderness when interest rates were at rock-bottom levels.

The fund is light on US exposure, holding just under one-third of its portfolio in the country. In contrast, the MSCI World Index, which follows the ups and downs of 1,320 global stocks across 23 developed markets, holds 72% in US companies. It launched 15 years ago, and the same stock picker – Jacob de Tusch-Lec – remains at the helm. 

Seven of the eight other funds and investment trusts in the top 10 have made re-appearances in the table. The biggest mover, up five places to fifth, is renewable energy infrastructure investment trust Greencoat UK Wind (LSE:UKW).

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There’s just one new entry, Polar Capital Technology. Managed by Ben Rogoff, it owns tech firms around the world, including NVIDIA Corp (NASDAQ:NVDA), Taiwan Semiconductor Manufacturing Co Ltd ADR (NYSE:TSM), Microsoft Corp (NASDAQ:MSFT) and Meta Platforms Inc Class A (NASDAQ:META). It takes a “benchmark-aware” approach, resulting in it owning most of the biggest names in the sector. Rogoff has managed the investment trust for nearly two decades.

Funds and trusts section written by ii’s Kyle Caldwell.