At one time, an initial public offering was considered de rigueur for growing companies — a seemingly endless availability of capital plus the panache conferred by a public listing helped spur an avalanche of filings that swelled to more than 600 in 1996. But a spate of regulatory burdens — like the Sarbanes–Oxley Act – raised the costs of going public, helping to curtail IPOs while spurring more interest in alternative capital sources, say experts from Wharton and PricewaterhouseCoopers.