NK clock, Neon clock at Nordiska Kompaniet department store, Stockholm, Sweden

The NK clock is a rotating neon sign on a roughly 25-metre mast on the roof of the Nordiska Kompaniet department store at Hamngatan 18–20. The seven-metre disc shows the green NK logo on one side and a red clock face on the other, turning once every 15 seconds.

Designed and built in 1939 by Ingenjörsfirman Teknik ASEA with Ruben Morne, the sign was first lit on 2 October 1939 atop the 45-metre Telefontornet, built in 1887 near Brunkebergstorg. It was taken down on 15 September 1952 before the tower's demolition and remounted in December 1953 on a roughly 25-metre mast on NK's roof. In 1983 it was removed for renovation, and in 2012 its 92 metres of neon tubing were replaced with LED.

The green NK logo and red clock face serve as a daily reference point for people moving through Stockholm's center, helping them navigate and orient themselves. Passersby naturally glance upward at this familiar landmark as they go about their day.

The sign sits on a roughly 25-metre mast on the NK roof, reached by a spiral staircase designed by Hans Asplund. It is best viewed from Hamngatan or Kungsträdgården, where both the green logo and the red clock face come into view as it turns.

The clock weighs 7 tonnes, and its minute hand alone is 4.5 m long and weighs 44 kg. When erected, 22 mm neon tubes with a total length of 105 m were mounted on each side, and weatherproof transformers were built into the dial. In 2012 the 92 m of neon tubing was replaced with LED technology by Focus Neon, cutting energy use to a tenth.