Vodafone has swung to a full-year loss and cut its payout to shareholders for the first time.
The reduction in the dividend to 9 euro cents a share from 15.07 cents contradicts a pledge in November by new chief executive Nick Read to maintain the payout.
The mobile phone giant pays one of the biggest dividends in the UK.
The €7.6bn (£6.6bn) full-year loss was in part caused by a transaction in India. A year ago profits were €2.8bn.
Among the other reasons for the loss was a reduction in the value of investments in Spain and Romania.
Revenues in the year to March fell 6% to €43.7bn.
Floated on the stock market as part of Racal Telecomms in the 1980s, Vodafone made the world's first mobile phone call from London to Newbury - where it still based - in 1985.
But since then it has expanded beyond mobile phones, buying broadband companies in countries such as Germany and Spain, and is now incurring big bills to build 5G networks.
It is also in the process of taking over some of the assets of Liberty Global in what it is its biggest deal since its £112bn takeover of German company Mannesmann in 2000.
In the process it has amounted debt - it had €27.0bn of debt at the end of its financial year, down from €29.6bn a year earlier - and it also needs to invest in 5G networks.
Mr Read said the group was at a "key point of transformation".
He is aiming to cross-sell additional products, such as broadband, cut operating costs and is setting up a new division for Vodafone's European mobile towers.
"We are executing our strategy at pace and have achieved our guidance for the year, with good growth in most markets but also increased competition in Spain and Italy and headwinds in South Africa," Mr Read said.
"These challenges weighed on our service revenue growth during the year, and together with high spectrum auction costs have reduced our financial headroom."
He said the dividend was being "rebased" to allow further growth and cut back on debt.
Chris Beauchamp, chief market analyst at IG, told BBC Radio 4's Today Programme: "Vodafone is a huge dividend payer and so [it's] important.
"The fact they've been expanding heavily has meant they need to now cut back on the dividend to pay down all the debt they've acquired."
Vodafone started paying dividends in the 1990s, and its payouts amount to about €3.5bn a year.