Should the SARB start doing QE, however, by buying bonds on the secondary market, then investors could shift risk back onto the public sector’s balance sheet, at a higher price. In other words, it would be a private sector bailout, arranged by the SARB.
Worse, QE would reduce the incentives for new investors to come and buy long-term sovereign debt, because there would not be enough yield or compensation for the longer-term risks now visible. What happens with QE, instead, is that public borrowing switches to the short-end of the curve.