Omar El Mghari

Omar El Mghari is the founder of PMSOX and a former chief financial officer and head of internal audit. When his son Hassan El Mghari built an app that used AI to forecast Costco’s membership fee revenue, Omar drew on his audit experience to explain a puzzling result: correcting a figure with Costco’s own data made the forecast less accurate.

Omar started programming at 16 with a tennis game he wrote in BASIC on an Epson computer. The ball took nearly a minute to cross the screen. With his brother’s help, he learned assembly language and rewrote the game. This time he had to slow the ball down to see it.

Over 25 years in finance, Omar worked at Big Four audit firms, held CFO roles and led internal audit at a multibillion-dollar company. When he returned to programming, Hassan helped teach him. One project grew out of a bookkeeping chore Omar was tired of doing by hand. He built a tool to convert PDF bank statements into CSV files ready to import into QuickBooks.

In the Costco project, Omar traced the model’s estimate that 15% of members paid for the higher-priced Executive tier to a passage that said only that the share was growing. Costco had disclosed the figure elsewhere: 45%. When Omar substituted that figure and left everything else alone, the forecast error jumped from 1.7% to 28%. The correction exposed a second mistake. The model had applied a US and Canadian fee increase to members worldwide, and its low estimate of the Executive share had masked the overcount. Hassan and Omar turned several of Omar’s accounting checks into code, including one that checked the Executive share against Costco’s disclosure.