Edizione, which owns a 16.45% stake in Cellnex according to Refinitiv Eikon data, said on Friday it had signed a contract to sell the equivalent of 3.4% of Cellnex shares to Goldman Sachs.

The investment bank, to protect itself from a potential price downturn, sold a similar sized stake in the company through an accelerated bookbuilding operation on Friday.

The Cellnex shares were sold at 57 euros each, about 6.2% below the market closing price on Thursday. The whole stake was worth 753 million euros ($874 million), Goldman Sachs said.

After the capital increase, Edizione will still hold 13% in Cellnex and will remain its largest shareholder.

"Edizione reiterates its firm support to Cellnex's current strategy and the capital increase as well as the management and future growth of Cellnex," the investment firm said in a filing to Spanish stock market regulator.

Cellnex said on Wednesday it planned to raise cash through the sale of new shares to finance the expansion of its infrastructure portfolio.

(Reporting by Inti Landauro; editing by Jason Neely and Mark Potter)