Gold production fell 7% year-on-year in the first quarter to 588,000 ounces - 11% below consensus estimates - with COVID curbing output at its assets in Brazil and Argentina by about 4000oz.
The company reported lower grades and throughputs as it focused on waste stripping and underground development while utilising stockpiled material.
The production result missed RBC Capital Markets' forecast by 12%.
RBC has also downgraded AngloGold's 2021 production and EBITDA forecasts by 4% and 3% respectively, although AngloGold reiterated its production guidance figures for the year.
Total cash costs rose 29% to $999/oz in Q1 - 10% higher than RBC's estimate - which the miner blamed on lower grades and drawing down on ore stockpiles at some operations plus inflationary pressures.
The JSE-listed miner reported headline earnings of US$203 million or 48c per share - driven by the higher gold price.
Adjusted EBITDA increased by 3% to $449 million but missed RBC's forecast by 15%.
AngloGold also slashed net debt by 43% year-on-year to $908 million during the quarter.
Interim chief executive Christine Ramon said the company's strategy to boost investment in brownfield exploration was on track and the redevelopment of Obuasi is "making steady progress" and was 97% complete at the end of March.
Obuasi production rose 53% quarter-on-quarter in Q1 to 46,000oz.
Analysts at BMO Capital Markets pointed to a feasibility study for its Quebradona project in Colombia - due in August 2021 - as the next key catalyst for the company.
The bank also downgraded AngloGold's target price by $1 to $22.
AngloGold dropped 2% on Monday in New York to $22.63.