As investors continue to pile into U.S. corporate debt and issuers ramp up borrowing, S&P Global Ratings continues to warn about deteriorating credit quality.

The third quarter saw the most credit ratings downgrades for U.S. companies relative to upgrades since 2015, according to S&P data compiled by Bloomberg.

The credit rating agency issued downgrades for 164 issuers compared to 64 upgrades, good for an upgrade to downgrade ratio of 0.39. The majority of those cuts, 143 in total, were applied to the high-yield corner of the market compared to just 33 upgrades.

Among the most prominent downgrades was for WeWork which saw its rating slashed further into junk. The company, officially called We Co., now stands at the edge of the market’s weakest tier of borrowers.

Investment-grade debt fared better with a positive upgrade to downgrade ratio. In that space, 31 issuers received a ratings boost compared to 21 downgrades.