Børsen (English: The Stock Exchange) is a building on Slotsholmen in central Copenhagen, Denmark. It was built by Christian IV in 1619–1640 and is the oldest stock exchange in Denmark. It is known especially for its Dragon Spire shaped as the tails of four dragons twined together, reaching a height of 56 metres.
Christian IV had ambitions to turn Copenhagen into a metropolis and to strengthen the city's position as a commercial centre, he wanted a stock exchange along with the new merchant town Christianshavn he was constructing on the other side of the harbour. He asked Lorentz and Hans van Steenwinckel the Younger to design a building in Dutch renaissance with 40 small stalls at the ground floor and one big room at the upper floor.
The building was restored by Nicolai Eigtved in 1745 and internally renovated in 1855. It housed the Danish stock-market until 1974. In 1918, unemployed anarchists attacked Børsen, an attack that went to the Danish history books as "stormen på Børsen" (the storm at the stock exchange).