Deregulation in the US energy markets in the late 1990s provided Enron with trade opportunities, including buying energy from cheap producers and selling it at markets with floating prices. Andrew Fastow was familiar with the market and knowledgeable in how to play it in Enron's favor. This quickly drew the attention of then chief executive officer of Enron Finance Corp Jeffrey Skilling. Skilling, together with Enron founder Kenneth Lay, was constantly concerned with various ways in which he could keep company stock price up, in spite of the true financial condition of the company.
Fastow designed a complex web of companies that solely did business with Enron, with the dual purpose of raising money for the company, and also hiding its massive losses in their quarterly balance sheets. This effectively allowed Enron's audited balance sheet to appear debt free, while in reality it owed more than 30 billion dollars at the height of its debt. While presented to the outside world as being independent entities, the funds Fastow created were to take write-downs off Enron's books and guaranteed not to lose money. Yet, Fastow himself had a personal financial stake in these funds, either directly or through partners amongst them Michael Kopper. Kopper, Fastow's chief lieutenant, pleaded guilty to taking part in a scam with Fastow that defrauded Enron shareholders of many millions. While defrauding Enron in this way, Fastow was also neglecting basic financial practices such as reporting the "cash on hand" and total liabilities. Fastow pressured some of the largest investment banks in the United States, such as Merrill Lynch, Citibank, and others to invest in his funds, threatening to cause them to lose Enron's future business if they did not. Fastow also reportedly got these firms to fire their analysts who dared to report Enron with negative ratings.