Royal Schiphol Group has sold off its remaining stake in French airports company Aeroports de Paris (ADP), ADP said on Tuesday, prompting ADP's shares to slump as the sale took place at a sharp discount to ADP's recent share price.

ADP said Royal Schiphol had sold off the shares at a price of 133 euros per share - a sharp discount to ADP's closing share price of 147.65 euros on December 5.

ADP added that the proceeds from this transaction to Groupe ADP amounted to around 420 million euros ($440.2 million).

ADP shares were down 13.68% at 127.05 euros in early session trading - the worst performer on France's SBF-120 index . The French state owns just over 50% of ADP's share capital.

"The sale of multiple smaller stakes and a block trade implies in our view there were no strong candidates for the whole stake," RBC said in a note.

It "is therefore more negative in terms of sentiment and catalyst for ADP stock price than could have been," the brokerage added.

Royal Schiphol had already sold in November a 2.5% stake in ADP to Credit Agricole and a 1.6% stake to Canada Pension Plan Investment Board.

($1 = 0.9542 euros) (Reporting by Clement Martinot and Dominique Vidalon; Editing by Jacqueline Wong/Sudip Kar-Gupta)