The Fitch agency has downgraded South Africa's credit rating to junk status, citing political turmoil and governance concerns.
The downgrade on Friday followed a similar move earlier this week by the Standard & Poor's ratings agency. It came as thousands of protesters across the country called for President Jacob Zuma to resign following his dismissal of the finance minister in a Cabinet reshuffle.
Fitch says the reshuffle, in which widely respected Finance Minister Pravin Gordhan was fired, will further discourage companies from investing in South Africa. It also says the unsettled political situation is likely to weaken "standards of governance and public finances."
The ruling African National Congress party has been hurt by scandals surrounding the president, and some party members have called for Zuma to quit.