Demand at 40-year JGB auction sinks to lowest since July

(Corrects milestone to July from November in headline and first paragraph)

By Kevin Buckland

TOKYO (Reuters) -Demand at an auction of 40-year Japanese government bonds on Wednesday fell to the lowest since July, amid a selloff in so-called super-long debt this month.

A measure of demand called the bid-to-cover ratio, which gauges total bids against the amount of securities on offer, sank to 2.2 from 2.9 at the previous sale in March.

Japan's Ministry of Finance sold about 500 billion yen ($3.46 billion) of the bonds at Wednesday's auction.

The 40-year JGB yield spiked to a record 3.675% last week as worries about the debt load in Japan and other developed markets like the United States led to a sell-off in the longest-dated bonds.

Super-long JGBs lacked the support of traditional buyers like life insurers and pension funds, who have been scaling back purchases.

($1 = 144.5200 yen)

(Reporting by Kevin Buckland; Editing by Jamie Freed and Sam Holmes)