General Motors (NYSE:GM) raising $4 billion in bond offering designed further bolster its balance sheet amid the coronavirus pandemic. 

In a filing with the Securities and Exchange Commission Thursday evening, GM explained that its bonds are "senior unsecured notes" — "senior" meaning that the bondholders have priority should GM be forced to liquidate and "unsecured" meaning that GM wasn't required to post collateral for the debt.

A GM sign atop the Renaissance Center, GM's corporate headquarters in downtown Detroit.

Image source: General Motors.

The bonds are in three separate series, with due dates ranging from 2023 to 2027. The 2027 bonds yield 6.8%, close to junk bond territory despite GM's investment-grade credit rating. 

That investors demanded such a high yield signals concern that GM's credit rating could be downgraded in the coming months. Rival Ford Motor (NYSE:F) lost its investment-grade credit rating on March 26.

While somewhat high given GM's credit rating, GM's bond yields are considerably lower than the yields on the bonds Ford issued in April. The yields in Ford's $8 billion bond issue ranged from 8.5% to 9.625%, with maturities ranging from 2023 to 2030.

GM's new bond issues were priced on Thursday and will settle on Tuesday, May 12. 

This is GM's first debt offering since the onset of the pandemic, which forced GM to idle its factories in North America in mid-March. GM plans to begin reopening its U.S. plants on May 18, but it's likely to run at a loss for at least a few months.