The share price for Spain's national aviation authority, AENA, has soared by 18 percent on the first day of trading after the state company was partially privatized.
The price jumped from an opening price of 58 euros ($65) to 68 euros after trading started at noon Wednesday.
The floating of 49 percent of AENA's stock was initially estimated to net the government about 4.3 billion euros. Based on the starting price, the company was valued at 8.7 billion.
The government will retain a controlling 51 percent stake in AENA. The sale is one of the biggest in Spain in recent years.
AENA operates 46 airports and two heliports in Spain, and has stakes in 15 other airports abroad.