The Nikkei 225 Stock Average rose 406.64, or 4.5 percent, to close at 9,521.24 in Tokyo. The gauge has rebounded 33 percent from a 26-year low on Oct. 27, its best six-day gain according to available data back to 1970. The broader Topix index surged 56.21, or 6.2 percent, to 966.91