More than two years after departing the wealth giant his father founded, former La Trobe Financial president Greg O’Neill has resurfaced as a big-money backer in a ploy to net billions of dollars in oil and gas proceeds from a clerical error at Chevron.

Filings with the Securities and Exchange Commission in the United States show Mr O’Neill’s family office, Watermill Capital Partners, has been pouring money into Nasdaq debutant Prairie Operating Co at a rapid rate over the past 12 months.