When a big company needs money, it often does not go to a bank.

It borrows from investors by selling bonds, IOUs that pay interest for years.

In 2025, companies did this at a record pace, and most of that debt ends up in your funds.

U.S. investment-grade companies sold well over $1.5 trillion in bonds in 2025.

It was one of the busiest years on record, outside the pandemic surge.

September 2025 saw the most separate deals of any month ever.

The rush had a reason: a wall of old, cheap debt from 2020 and 2021 was coming due.

Companies refinanced it while investors were eager to buy.

A company hires banks to arrange the sale.

The banks line up buyers, mostly pension funds, insurers, and bond funds.

The company sets a size, a maturity, and an interest rate to attract them.

If demand is strong, it can borrow more and pay a little less.

The bonds then trade among investors, and their prices move with rates and risk.

Most of that debt lands in the funds inside your retirement account.

The first stress point is refinancing. A company must sell new bonds to repay old ones.

If markets freeze when its debt comes due, it can be caught short.

The second is the spread, the extra yield over Treasuries that pays for risk.

In 2025 that spread was near its tightest in 15 years, so investors were paid little for risk.

The third is rates. When rates rise, existing bonds lose value, and holders feel it.

The corporate bond market is vast, liquid, and well-tested, and it funds much of the economy.

For strong companies, it is a reliable source of long-term money, and that deserves credit.

What can break is a refinancing wall meeting a closed market, or spreads too thin to cushion a shock.

You can watch the signals. Spreads and issuance volumes are reported regularly.

Very tight spreads mean investors are paid little to take on risk.

The corporate bond market lets companies borrow from investors at scale, and in 2025 they did so in record size.

The machine is sturdy, but thin spreads leave little cushion if the mood turns.

The next test is the next wave of maturing debt. Watch issuance volumes and credit spreads.