On this date, 11 December, the Romans used to celebrate Agonalia.
According to the useful Pagan calendar I mentioned yesterday, in Ancient Roman times, Agonalia, or Agonia, was a religious festival celebrated at various times of the year in honor of divinities such as Janus, the god of beginnings and endings, and Hermes Agonius, who presided over any solemn contest.
They influenced the realm of business endeavours and the Romans would call upon them when they undertook any new venture or important deal.
Agonalia was celebrated on January 9, May 21, December 11 and possibly March 17.
Here are some useful links