The Brazilian accounting unit of PricewaterhouseCoopers LLP reached a $50 million settlement of pension fund investor claims that auditors ignored red flags in a broad kickback and fraud scandal involving the state-run energy giant Petrobras.

The auditing settlement brought the total recovery amount to $3 billion in the resolution of consolidated litigation against Petroleo Brasileiro SA, as Petrobras is formally known. It was filed Feb. 1 as part of a submission in the U.S. District Court for the Southern District of New York seeking preliminary court approval of the wider agreement, which plaintiff attorneys said is the largest securities class...