This comes as a bitter blow for Patrick Drahi, whose ailments began during his attempt to take control of BT. Besieged on all sides, the Franco-Israeli tycoon, whose stake was bought by the Indian group Bharti, was forced to leave the table just before the game became interesting again, and before its market capitalization doubled in the space of 24 months.

However, BT's troubles are far from over, due to overcrowded competition. The erosion of its subscriber base continues, with 825,000 broadband lines lost to competitors in 2025, and a similar forecast for 2026. In mobile, the UK's third-largest operator is limiting the damage but can hardly hope for growth in its subscriber base or an increase in plan pricing.

Over the last decade, revenues have fallen by a fifth, its operating profit by a quarter, and its net income has been halved. It has not made any capital increases, although net debt has doubled, notably to finance the rollout of the Openreach fiber network. This has placed free cash flow under pressure and has resulted in it halving its dividend per share.

How can the recent stockmarket rally be explained, if not by a shift in investor sentiment extended to the entire European telecoms sector, which has traditionally been shunned by them? First, the group can now count on the support of Bharti Enterprises, an industrial player with deep pockets and a long-term vision.

Second, BT has said that its investment program has peaked, and that capital intensity should now decrease. Caution is warranted, however: this refrain, as old as copper wire itself, is repeated through cycles by all operators, only to be generally and rapidly refuted by circumstances.

The fact remains that the stock's current valuation appears generous: the stock's dividend yield is 100bp lower than 10-year UK Gilts, and its enterprise value of £42bn represents nearly triple what BT has already invested in Openreach - a figure which, admittedly, certainly underestimates the actual replacement cost.

Even if this amount were doubled, it would leave £12bn of valuation for the mobile network of 14 million subscribers and the remainder of the enterprise and services businesses in structural decline. By all measures, BT therefore appears to be very leniently valued.

It is now up to the operator to deliver on its commitments - a sustainable reduction in fiber network investment; stabilization of subscriber numbers; and significant growth in average revenue per user (ARPU) in the fiber segment - failing which, a market correction will be inevitable.