He traded within Denmark–Norway and with the Russian Empire (what today is Poland, Russia, Estonia, Latvia and Lithuania).

He constructed the Niels Brock House at 36 Strandgade in the Christianshavn neighbourhood of Copenhagen in 1780 and lived there until his death in 1802.

[2] At the event of his death in 1802, Niels Brock left an estate of 865,000 kurantdaler which was used for grants in Randers and Copenhagen.

This was done under the auspices of the Association for the Education of Young Merchants (Foreningen til Unge Handelsmænds Uddannelse realiserede) in 1881 under the name Købmandsskolen i København.

Carl Frederik Tietgen, who was a member of the board of the foundation that administrated Brock's heritage, founded an advanced school of merchantry under the name De Brockske Handelsskoler in 1888.