TOKYO, July 9 (Reuters) - Japanese government bond prices were mostly firmer on Wednesday, lifted by sagging Tokyo shares and an overnight rally by U.S. Treasuries.
Superlong JGB maturities lagged slightly, weighed by Thursday's 700 billion yen ($6.9 billion) 30-year debt auction.
September 10-year JGB futures climbed 0.06 point to 145.78.
The benchmark 10-year yield stood unchanged at 0.550 percent, matching a 15-month low hit the previous week. Yield on the superlong 20-year bond, on the other hand, rose 0.5 basis point to 1.425 percent.
Tokyo's Nikkei fell to a one-week low in the wake of a broad selloff on Wall Street.
U.S. Treasuries surged on Tuesday with investors raising their bond holdings as stock markets retreated before corporate earnings season, while overseas trade data fueled worries about global economic growth. ($1 = 101.5400 Japanese Yen)
(Reporting by Shinichi Saoshiro; Editing by Eric Meijer)