TOKYO, Dec 5 (Reuters) - Japan's Nikkei share average fell on Monday after Italian Prime Minister Matteo Renzi's defeat in a constitutional reform referendum gave investors an opportunity to sell into a market that had rallied to 11-month highs late last week.
The Nikkei dropped 0.8 percent to 18,274.99, its lowest closing level since Nov. 22.
Tokyo's banking sub-sector index underperformed to lose 1.8 percent amid caution over the referendum's effect on Italy's banking system.
The broader Topix and the JPX-Nikkei Index 400 both fell 0.8 percent to 1,466.96 and 13,156.93, respectively. (Reporting by Shinichi Saoshiro; Editing by Simon Cameron-Moore)