Orange is selling around a third of its stake in BT, just five months after the French state telecoms monopoly was released from a lock-up preventing a share sale.
Orange currently holds a 4pc stake in its BT, with the 398.7m shares taken as part-payment for 50pc of EE, the mobile operator BT acquired for £12.5bn last year.
However, since then, the value of its stake in BT has fallen from £1.7bn to £1.15bn. Shares are down 21pc in the year to date alone.
In January, the value of Orange's stake fell by £300m in one day, as news emerged of an accounting scandal at BT's Italian business and the group reported weak trading in its public sector and international corporate business.
When Orange was released from the lock-up earlier this year, analysts had voiced concerns that should Orange offload the stake, it would likely put a brake on any recovery in BT’s share price.
The 1.44pc stake Orange plans to sell is around equal to around 133m shares, or a third of its entire holding in BT.
Shares in BT closed down 0.48pc at £2.897 on Monday, although the announcement of the expected sale came after London markets closed.
BT said it planned to buy shares worth around £200m from Orange, equal to around 66.5m of the shares up for sale, citing its statement in May in which it voiced expectations it would buy back around £100m shares in the current financial year.
BT said it had "decided to take advantage of current market conditions and the opportunity to purchase a significant number of shares in a single transaction by participating in the offering in excess of the level previously expected for the 2017/18 buy back".
Together with the planned sale, Orange also launched an offering of four-year convertible bonds exchangeable into BT shares for £520m, equal to another third of its stake.
As such, it is initially retaining a 2.66pc stake in BT, but if exchange rights are fully exercised, it would retain a 1.33pc stake in BT.