Times are tough for the Mall at Stonecrest in suburban Atlanta. The Kohl’s closed in 2016. The Sears shut in 2018, and the Payless ShoeSource finished its going-out-of-business sale in May. When a $90.5 million mortgage came due last summer, the mall’s owners defaulted.

Through it all, S&P Global Inc. has said a security tied to the mall’s mortgage wouldn’t lose money. S&P says the “situation is fluid” and “we won’t hesitate to revisit the rating.”

Inflated bond ratings were one cause of the financial crisis. A decade later, there is evidence they persist. In the hottest parts of the booming bond market, S&P and its competitors are giving increasingly optimistic ratings as they fight for market share.

All six main ratings firms have since 2012 changed some criteria for judging the riskiness of bonds in ways that were followed by jumps in market share, at least temporarily, a Wall Street Journal examination found. These firms compete with one another to rate the debt of borrowers, who pay for the ratings and have an incentive to pick rosier ones.

There are signs some investors are skeptical. Some bonds in markets where ratings criteria have been eased don’t trade at the high bond prices their ratings suggest they should. Investors have also shown skepticism about ratings on some corporate and government bonds.