JPMorgan Chase & Co. building in New York. (Mike Segar/Reuters)

It's an end of an era at JPMorgan Chase. Blythe Masters, widely credited as an architect of the notorious credit default swaps that helped fuel the financial crisis, is leaving after nearly three decades at the bank, according to an internal memo obtained by The Washington Post.

The news isn't all that surprising considering that the physical commodities business that Masters ran at JPMorgan was sold last month to Swiss trading firm Mercuria Energy Group for $3.5 billion. There was speculation on Wall Street that Masters would continue to run the bank's core commodities business -- the side that handles financial derivatives and the trading of precious metals.

Instead, the JPMorgan veteran has decided to "take some well-deserved time off and consider future opportunities," according to the memo. Masters plans to stick around for a "few months" as the bank hands over its physical commodities business to Mercuria.

That division was at the center of a regulatory firestorm that left Masters' reputation singed. Back in July, the Federal Energy Regulatory Commission slapped JPMorgan with a $410 million penalty over allegations that it manipulated energy markets. The agency did not pursue charges against Masters, but evidence in the case cast her in a poor light.

The commission produced e-mails that showed Masters may have been aware of bidding strategies the firm used to charge electricity grids in California and the Midwest as much as 80 times the prevailing power prices. JPMorgan adamantly denied the charges and stood behind Masters throughout the ordeal.

Days before the settlement became public, the bank announced its intentions to exit the physical commodities business. The move came as lawmakers and some regulators grew weary of financial firms involvement in the commodities markets, with Wall Street banks not only assisting clients but also trading for their own accounts.

Buying up physical assets like storage tanks gave those banks the flexibility to accept delivery of and hold on to commodities such as oil, sugar, corn and metals. It also opened up the possibility for market manipulation, at least in the eyes of regulators.

In the face of growing scrutiny, most of the big banks, including Morgan Stanley and Goldman Sachs, have sold or are contemplating the sale of their own physical commodities units.

Heading the commodities unit at the nation's largest banks was one of many positions Masters held over the course of her 27-year career at JPMorgan. She joined the bank as an intern and quickly rose in the ranks. Along the way, she ran the North American asset-backed securities unit, global structured credit products, global credit portfolio and was the chief financial officer of the investment bank. All this, before she was appointed global head of commodities in 2007.

In the memo, JPMorgan chief executive Jamie Dimon and Daniel Pinto, head of the firm's corporate and investment bank, credit Masters with building the commodities business "into the industry-leading franchise it is today."

Dimon and Pinto said the bank plans to announce a replacement for Masters "shortly."

Masters is probably best known for her role in designing products that Warren Buffet once called "financial weapons of mass destruction."

Twenty years ago, Masters led a team at JPMorgan in creating a type of insurance policy against credit risk. Companies selling these contracts would agree to pay investors if certain loans--like mortgages--went into default. The contracts became a hit on Wall Street and earned JPMorgan hundreds of millions of dollars.

Banks, pension funds, hedge funds and investment houses used the swaps to hedge their bets or produce elaborate trading strategies -- some of which would ultimately prove fatal to the economy.

Goliath insurer AIG got in on the action, selling billions of dollars of CDS that forced it to pay out billion of dollars after the subprime mortgage market blew up in 2007. Jobs were lost. Companies teetered on the brink of collapse. And taxpayers handed over $182 billion to keep AIG afloat.

Masters certainly didn't orchestrate any of this, but she arguably helped lay the groundwork. And her name will forever be synonymous with credit default swaps.