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. 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 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.