The following is a chronology of major events related to the 225-issue Nikkei Stock Average. September 1985 — Britain, France, West Germany, Japan and the United States sign the Plaza Accord to stop the U.S. dollar’s rise against other major currencies, prompting the Bank of Japan to cut the official discount rate that had led to an asset-inflated economic bubble. Dec. 29, 1989 — The Nikkei index closes at what was an all-time high of 38,915.87 and hits an intraday record-high of 38,957.44 amid the bubble economy. November 1997 — Major Japanese securities firm Yamaichi Securities Co. collap…