This post is part of a feature in which he wonder whatever happened to some notorious financial felons. See all 17.

Mike Milken turned the market for bonds issued by less creditworthy companies into a gold mine for himself and his firm, Drexel Burnham. As I posted, this did not end well. But in the past several years, Milken has worked hard to rehabiliate his reputation -- putting money into prostate cancer research and talking about the economy.

Who is Milken and how did he get here? Mike Milken was an academic star. He used to take the bus back and forth to classes at Wharton and came in to school before dawn with a miner's hat on his head because the bright light helped him read annual reports. Milken and I studied with the same management professor at Wharton.

That professor predicted that Milken would either make a huge amount of money or go to jail. He did both -- eventually agreeing to pay $650 million in fines and plead nolo contendere to six felonies -- three counts of stock parking and three counts of stock manipulation. Milken went to jail from March 1991 until January 1993. But that's ancient history. Where is he now?

This post is part of a series on some of the most memorable companies that have disappeared.

Drexel Burnham Lambert (1935 - 1990) spent its last decade accumulating money and power. The key was junk bond impresario Mike Milken, who used to take the bus back and forth to classes at Wharton and came in to school before dawn with a miner's hat on his head whose bright light helped him read annual reports.

Drexel's driving force, Milken, realized the potential of our shared management professor at Wharton. That professor predicted that Milken would either make a huge amount of money or go to jail. He did both. Milken made money by selling junk bonds to takeover artists who threatened companies by buying up their shares and proposing to throw out their managers. In many cases the companies bought out the takeover artist's shares at a premium to make them go away.

Milken was feared by the business establishment, and he had a contempt for the law. So he did himself in -- eventually agreeing to pay $650 million in fines and plead nolo contendere to six felonies -- three counts of stock parking and three counts of stock manipulation. Milken went to jail from March 1991 until January 1993. Drexel hemorrhaged capital; fired 5,000 people; and eventually filed for bankruptcy in 1990.

The lesson? If you can't achieve wealth within the law, you will pay the price.

Peter Cohan is President of Peter S. Cohan & Associates. He also teaches management at Babson College and edits The Cohan Letter.

Let us know in the comments what you remember about Drexel. And be sure to check out other Companies That Have Vanished.

The last three decades have oscillated between private equity and venture capital. Right now, VCs are down and private equity is up. But 'clean tech' -- technologies that save energy and otherwise allow for a cleaner, greener world -- could revive VCs in the next decade while private equity licks its wounds.

In the 1980s, private equity was king. LBO firms were able to borrow huge amounts from banks and the junk bond market to finance hostile takeovers. The LBO boom ended badly with the collapse of junk bond king Drexel Burnham and overreaching in the form of the bidding war for the largest LBO in history --- RJR Nabisco.

In the 1990s, private equity imploded and watched with envy as venture capital prospered. It wasn't until the middle of the decade that VC firms like Kleiner Perkins were able to prosper from their investments in the Internet – beginning with the 1995 IPO of Netscape. The dot-com boom ended badly in 2000 with NASDAQ plunging -- it's down 54% from its March 2000 peak of 5,038 to its current 2,327.