It’s decision time for the would-be owners of Hargreaves Lansdown.

A trio of private equity heavyweights have until Wednesday to make a formal offer for Britain’s biggest investment platform, or walk away. It follows their £4.7 billion tilt, spurned in April.

The unsolicited £9.85 per share approach marks a watershed for the firm, which looks after £142 billion of savings and pensions for its near-two million customers. It has upended the savings market since it was set up by Peter Hargreaves and Stephen Lansdown 33 years ago.

By cutting out fee-hungry intermediaries, they enabled millions of ordinary savers to choose and trade their own shares and funds.

It also made the co-founders multi-millionaires. They still own a quarter of the shares and are open to offers, effectively holding the fate of the firm in their hands.

Hargreaves, 77, the biggest single shareholder with a 20 per cent stake, told the Daily Mail he was ‘looking at all options’ and was ‘watching with interest’.

Lansdown, 71, told Bloomberg news agency. ‘It’s interesting to see third parties now seeing the value in Hargreaves Lansdown and looking to take advantage of it.’ Hargreaves has been a vocal critic of previous management, telling the Financial Times it had presided over ‘a shambles’ that had halved the share price.

He blamed soaring costs and a move into financial advice – a heavily regulated area that big banks and nimble digital players also have raced into.

The firm is still recovering from association with fallen stockpicker Neil Woodford, whose funds it promoted even as they sailed on to the rocks. It also has been criticised for its fees, charging an annual 0.45 per cent for investing on its platform, compared with 0.25 per cent for rival AJ Bell.

The Financial Conduct Authority is on the case, citing new consumer duty rules requiring finance firms to deliver ‘good outcomes’ for clients. The firm’s fees ‘nettle’ has ‘yet to be grasped’, said Andrew Crean at Autonomous, an independent research house.

What attracted bid interest is that Britain’s biggest fund supermarket makes most of it profit risk-free. It has been one of the biggest winners from the recent steep rise in interest rates because customers typically keep a tenth of their portfolio in cash.

The Bristol firm deposits this with the Bank of England at an overnight rate of 5.25 per cent, pays customers a lower rate of interest – 3 per cent on a cash Isa of up to £10,000 – and pockets the difference. This netted it £269 million last year – two thirds of profits – up from £50 million in 2022.

Other platforms such as AJ Bell and Interactive Investor also make a mint this way – but they don’t dominate the sector.

Boss Dan Olley, who took over last year, has reined in costs and cut back on digital advice.

But analysts fear he may not have time to deliver his strategy.