April 9 (Reuters) - The U.S. corporate bond market has

shut again after opening for just one bond offering on Tuesday,

as spreads in the week after President Donald Trump's Liberation

Day tariffs have widened the most since 2023's regional banking

crisis.

Since Trump's tariff announcements exactly one week ago on

April 2, corporate bond spreads, or the cost to borrow, have

widened to their highest levels in nearly two years.

Both investment-grade and junk bond spreads have seen the

most one-week widening since the regional banking stress in

March 2023 that resulted in the woes of Silicon Valley Bank and

other banks, according to Dan Krieter, director of fixed income

strategy at BMO Capital Markets.

The bond market's first new deal in three days occurred on

Tuesday, a $4.2 billion, three-part transaction from human

resources provider Paychex ( PAYX ). It was the first deal since

Swiss cement maker Holcim's four-part, $3.4 billion

issuance on April 2.

High-grade bond spreads tightened 2 basis points on Tuesday

and last sat at 118 bps as of market close, according to the ICE

BofA indexes. Junk bond spreads were 4 bps

tighter at 457 bps.

But both the high-grade and junk bond spreads may have

widened again on Wednesday morning, driven in part by early

morning U.S. Treasury market volatility, as Chinese and other

Asian funds offloaded Treasuries in high volumes.

One senior syndicate banker said Paychex's ( PAYX ) bonds were

trading a couple of basis points tighter at the start of the day

but then were quoting 3-4 bps wider by midday.

Benchmark 10-year U.S. Treasury note yields

jumped to a seven-week high 4.515% on Wednesday.

"Risk sentiment is once again sharply lower this morning,

likely keeping any borrowers on the sidelines as issuers

continue to wait for any semblance of calm that remains

elusive," said Krieter.