Fresh from a run of weekly gains pushing it to its best monthly gain since January, the rand could be in for a rocky ride as investors await details of finance minister Tito Mboweni’s plans to fix SA’s fiscal position and appease credit-rating agencies.

Mboweni’s medium-term budget policy statement on Wednesday will probably confirm that a weak economy, tax-collection shortfalls, and bailouts for state-owned enterprises such as Eskom will saddle SA with its widest budget deficit in a decade.

Economists will be on the lookout for a credible plan from the minister to cut spending or boost revenue...