* Yen suddenly jumps to 3-month high, raising speculation of

more intervention

* Retreat in equities led by automakers as currency strength

sours outlook

* JGB yields rise as intervention seen pressuring BOJ to

hike rates sooner

By Kevin Buckland

TOKYO, Aug 3 (Reuters) - The yen leapt on Monday, while

stocks and bonds fell after Tokyo confirmed a rare joint

currency intervention with Washington to pull the Japanese

currency off four-decade lows.

The yen jumped as much as 1.4% in the Asian morning

155.20 per U.S. dollar, a level last seen on May 6. The sudden

surge provoked speculation among market participants of another

round of intervention, following the joint action last week,

with the yen surging 3.8% over Thursday and Friday.

However, Japanese Finance Minister Satsuki Katayama declined

to comment on whether her ministry had intervened in the market

on Monday.

"The coordinated intervention has materially raised the cost

of betting against the yen," said Charu Chanana, chief

investment strategist at Saxo. "It not only caught speculative

positioning offside but also increased the risk of follow-up

action, which should make investors more cautious about

rebuilding aggressive short-yen positions."

The sudden strength in the local currency weighed on

Japanese stocks. The Nikkei retreated sharply from

Friday's one-week high, sliding as much as 2.6% in the morning

session, while the Topix tumbled 3.1%. A stronger yen

slashes the value of overseas revenue for the country's many

heavyweight exporters.

Automakers were the worst performers among the

Tokyo Stock Exchange's 33 industry groups, dropping 4.2%. Toyota ( TM )

slumped 4.6%.

Japanese government bonds also declined, sending yields

higher, as some investors took joint intervention as a signal

for an accelerated pace of Bank of Japan policy tightening.

"Japan and the U.S. conducted joint currency intervention,

which means Japan is under pressure to support the yen with

fundamentals this time, such as with monetary policy," said

Rinto Maruyama, senior strategist of FX and rates at SMBC Nikko

Securities.

The yen has been under pressure for years, undermined by the

BOJ's gradual approach to monetary policy tightening, which has

kept yield differentials wide between Japan and the rest of the

world.

U.S. Treasury Secretary Scott Bessent said Washington "will

not hesitate to participate in further joint intervention,"

while repeating calls for further interest rate hikes from

Japan's central bank.

The BOJ kept its policy rate steady on Friday, but warned

for the first time that underlying inflation could exceed its

target and said future policy discussions would focus on upside

price risks.

The yield on Japan's 2-year government bond,

the tenor most sensitive to monetary policy expectations, rose

as much as 4 basis points to 1.545%, a three-decade high.

The 10-year JGB yield added 2 basis points to

2.815%.

"Bessent's comments arguably carry more weight than the

intervention itself," said Matt Simpson, senior market analyst

at StoneX. "It feels like a safe bet that the Japanese yen has

troughed for the year."

(Reporting by Kevin Buckland; Editing by Varun H K)