Valencia biotech firm MannKind Corp.'s stock fell 11% Thursday after reports that a former senior manager said he had uncovered potentially serious problems with clinical trials of the company's experimental insulin inhaler.

The Food and Drug Administration is reviewing the Afrezza inhaler and is expected to make a decision Dec. 29 on whether to approve it.

The former MannKind manager, John Arditi, filed a lawsuit against the company in New Jersey Superior Court, saying he was wrongfully fired after internal audits he conducted in November 2009 uncovered "potential fraud and scientific misconduct" involving Afrezza clinical trial data. The lawsuit, which was filed in September, was first reported on TheStreet.com.

Arditi, who worked in a MannKind facility in New Jersey, said in the lawsuit that he urged his superiors at the firm to report his findings to the FDA but that the company refused because "if the FDA was notified of these concerns, it might delay approval" of the inhaler.

MannKind addressed the lawsuit in its most recent quarterly earnings report, stating that the company had completed an internal investigation into Arditi's claims and had hired an outside firm to conduct an independent investigation.

"Neither investigation found any basis for his claims," MannKind said. "The company believes that the allegations in the complaint are without merit and intends to defend against them vigorously."

Matthew J. Pfeffer, MannKind's corporate vice president, said the company was working on a legal response to the lawsuit. MannKind has until Dec. 3 to file its response in court, Pfeffer said.

MannKind has yet to share with the FDA the findings of its internal investigation or of the independent investigation, he said.

Shares Radian Group Inc. tumbled Monday after the mortgage insurer announced a public offering of convertible notes and disclosed it received a government subpoena.

Radian said it's publicly offering up to $350 million in convertible senior notes due 2017. The underwriters have the option to buy an additional $52.5 million of notes. The company said it plans to enter in a "capped call" to prevent the dilution of its shares once the debt is converted to stock.

But that did little to ease investor concerns. The stock of the Philadelphia company dropped $1.16, or 12 percent, to $8.79 in early afternoon trading.

The company also said Monday in a Securities and Exchange Commission filing that it received a subpoena from the U.S. Department of Housing and Urban Development asking for information on the company's captive reinsurance.

Under certain so-called "captive reinsurance" programs, insurers and lenders share premium revenue but also split exposure to any losses when borrowers default. Insurers take the primary loss, and lenders bear secondary exposure up to certain limits, after which insurers are saddled with the additional losses.

The Dow Jones industrial average rose 13 points in morning trading, again putting it in range to close at its highest level in more than two years. Broader indexes were mixed.

By the end of the trading day, investors will likely know exactly how much the Fed plans to spend to stimulate the economy. The central bank has hinted for two months it plans to buy Treasurys to drive interest rates lower in an attempt to spark lending and spending. However, there was still plenty of debate about the size and length of the program, particularly in the past few days.

The Fed is expected to announce details of its plan when it wraps up its meeting Wednesday afternoon. Treasury prices rose slightly, sending interest rates lower ahead of the announcement.

The Dow rose 12.75, or 0.1 percent, to 11,201.32 in morning trading.

The has been flirting with its highest closing level of the year, which was 11,205.03 on April 26. If it can close above that level, it would be the Dow's best finish since September 2008, just before the financial crisis peaked.

The Standard & Poor's 500 index rose 0.75, or 0.1 percent, to 1,194.32, while the Nasdaq composite index fell 0.36, or less than 0.1 percent, at 2,533.16.

The yield on the benchmark 10-year Treasury note, which moves opposite its price, fell to 2.56 percent from 2.59 percent late Tuesday.

Key economic reports that would have normally affected trading are being overshadowed by the Fed's meeting.

Two Tulsa men were sentenced Friday to lengthy prison terms after being found guilty in a multi-million dollar stock-fraud conspiracy, however a federal judge opted not to put them behind bars for life as he could have under applicable sentencing guidelines.

George David Gordon, 48, was ordered by U.S. District Judge James Payne to serve 15 years and 8 months in prison while Richard “Rick” Clark, 62, was given a 12 year, seven-month term.

Both men will be expected to contribute towards more than $6.1 million in restitution and to serve three years under court supervision after their eventual release from prison.

Payne had already issued a written order that contained a criminal forfeiture judgment against Gordon and Clark for more than $43.9 million.

The amount--specifically $43,927,809.95---is meant to represent stock sale proceeds traceable to the conspiracy that the jury found existed when it returned its guilty verdict, which was reached on May 3.

Also in the same Sept. 15 order, Payne entered another criminal forfeiture judgment against Gordon for more than $2.7 million, an amount related to a wire fraud charge of which Gordon was also convicted.

Gordon and Clark were among five men who were indicted in the case Jan. 15, 2009. They were accused of plotting from 2004 through 2006 to “pump up” the stock of three companies and then dump the stocks quickly at the expense of investors.

The two also were convicted of related crimes such as wire fraud, securities fraud and money laundering, although Clark was found not guilty of several counts, as well.

Gordon also was found guilty of obstructing justice and making a false statement in a matter within the jurisdiction of the U.S. Securities and Exchange Commission.

Federal sentencing guidelines would have allowed Payne to sentence Gordon and Clark to life in prison. However, Payne announced Friday that he would vary from the span recommended under the guidelines, which are advisory and not mandatory, Payne pointed out that following the originally recommended guideline punishment would have resulted in the two receiving a sentence greater than is often imposed in the nation’s courts for violent and or deadly crimes.

Even in the universe of financial crimes, Payne pointed out that major figures in the WorldCom and Enron scandals did not receive life sentences.

While Payne said the offenses of which Gordon and Clark were convicted were serious, he said they were simply “not in the same league” as the WorldCom and Enron scandals, both of which shook the financial markets.

Clark said nothing to the court during his Friday afternoon sentencing hearing. However, Gordon did apologize during his separate Friday morning hearing to his family as well as to any investors who have experienced “anguish and pain” due to his actions and to the Oklahoma Bar Association.

A Missouri business owner who claimed his company had assets that would make it the second biggest corporation in America has been charged with securities fraud and aggravated currency structuring.

Federal prosecutors said Wednesday that Petro America Corp., owned by Isreal Owen Hawkins, had no income other than investor money, no prospects for fulfilling its promises and only one full-time employee -- Hawkins. And instead of being worth more than $284 billion, as Hawkins claimed, Petro America's interests in gold mines and oil trading operations were worthless, investigators said.

"A federal criminal complaint alleges that Petro America was an empty facade of a business run by deception and false promises," U.S. Attorney Beth Phillips said Wednesday at a news conference. "Petro's founder is charged with defrauding unwary investors by selling them worthless stock in order to support his lavish lifestyle."

The criminal action comes on the heels of a civil complaint filed Friday seeking seizure of bank accounts and luxury items from Hawkins and other "unindicted co-conspirators."

Phillips didn't say Wednesday whether anyone else would be charged in the case.

Prosecutors said Hawkins, 55, of Kansas City, Kan., started selling unregistered stock to investors in 2008 at a cost of $100 per 100,000 shares, promising them that "book value" of the stock would be $2 per share when the company went public.