A 1998 concert in Philadelphia promoting alternative energy featured James Taylor and Kenny Loggins and exhibits like a Veggie Van, a purple mobile home fueled by used french-fry oil. The event's sponsor: GreenMountain.com, which markets electricity from sources like solar power and wind energy.

The company's chairman, Sam Wyly, still exhibits a flair for the dramatic, though his latest effort -- a $2.5 million advertising campaign that attacked the environmental record of Senator John McCain -- has raised questions about his tactics.

Critics charged that the ads, which praised the environmental policies of Gov. George W. Bush in Texas, were an unfair attack on Mr. McCain because they appeared just before last week's decisive Republican primaries. While Mr. Wyly and his brother Charles are major contributors to Mr. Bush, the ads were sponsored by "Republicans for Clean Air," a group recently formed by them.

The controversy has thrown a spotlight on Mr. Wyly, a 65-year-old Dallas investor who until recently was little known outside Texas, where he is part of a small circle of wealthy, politically connected Republicans. A founder of Maverick Capital Ltd., a hedge fund, he amassed an estimated $1 billion fortune in ventures as diverse as oil drilling, mining, software, steak houses and arts-and-crafts stores.

Mr. Wyly, who has collar-length hair and an energetic twang to his high-pitched voice, is relishing his moment, appearing on television and granting interviews. Though he and his brother are among the Bush campaign's biggest contributors, he insisted the ads were also an effort to promote his environmental interests.

"I'm a monomaniac with one goal," he said. "Clean air from clean energy."

He is also not a stranger to controversy. In 1979, Mr. Wyly settled Securities and Exchange Commission charges, and he was criticized recently by the California Public Employees Retirement System, one of the nation's largest pension funds, which said that he and other Wyly family members had favored themselves at the expense of shareholders.

And an investment by Maverick Capital in GreenMountain.com appears to be at odds with a past statement of a top fund official that it would not get involved in Wyly family enterprises because of potential conflicts.

These days, Mr. Wyly can barely restrain himself when he talks about the environment, an interest apparently ignited three years ago, after he, his family members, Maverick Capital and others invested $100 million in GreenMountain.com. Previously, he said, while he and his family had been large political donors to Republican causes, he had never contributed to an environmental group. "The air is dirty because of the electricity monopolists," he said excitedly. "They have powerful money lobbyists."

Since that investment, the company has successfully lobbied lawmakers in states like California, Pennsylvania, New Jersey and Texas to pass laws that deregulate energy markets by either encouraging alternative energy use or requiring that a small portion of the states' electricity pool -- up to 3 percent -- come from nontraditional sources. These include solar power, wind energy, and biomass, which involves the burning of organic matter like wood.

GreenMountain.com, which had been a unit of a Vermont utility, does not produce alternative energy but markets such power to mostly residential customers who are willing to pay a premium. In return, the company has said it will invest in alternative energy. It now has about 100,000 customers in California and Pennsylvania, and will soon market its services in other states.

Some environmental groups have criticized the company for buying energy from sources that for all their environmental claims, generate significant pollution. But the company has won the backing of other groups, and some said Mr. Wyly had lobbied hard to promote state and federal laws to deregulate energy. "He has been very aggressive in the market," said Scott Sklar, executive director of the Solar Energy Industries Association, a trade group. "When deregulation takes root, Wyly is going to make money."

Mr. Wyly is apparently not banking on deregulation alone to make money from GreenMountain.com. S.E.C. filings show that the company had weighed an initial public stock offering that would have valued the company at more than $3 billion, until it was withdrawn last year. At that price, the Wyly family's stake would have been worth about $1 billion. Mr. Wyly said the plan was withdrawn because the offering market was in a downturn.

GreenMountain.com, which markets its services over the Internet, uses the ".com" because it wants to be valued by Wall Street as a high-tech company rather than an energy supplier.

In the first quarter of 1999, it lost $19.8 million on revenues of $4.1 million, S.E.C. filings show.

A native of Louisiana, Mr. Wyly had his first success in 1963 when he founded University Computing, which operated a scientific supercomputer in office space borrowed from Southern Methodist University.

Mr. Wyly, a onetime head of Bonanza Steak Houses, a restaurant chain, later helped found Sterling Software, a high-tech company, which spun off Sterling Commerce, a business-to-business Internet company. He is also chairman of Michaels Stores Inc., a nationwide chain of arts-and-crafts supply shops.

A few of Mr. Wyly's ventures have failed, like Datran, a data transmission company that sought to challenge AT&T. But last month, Computer Associates International paid $4 billion to buy Sterling Software, and SBC Communications, in a separate transaction, purchased Sterling Commerce for $3.9 billion.

Today, Maverick Capital, which was founded in 1990 by Mr. Wyly and his son, Evan, manages more than $4 billion in assets from 700 institutions, including university funds.

A 1998 decision by the University of Texas Investment Management Company, a group that manages assets for the school, to place some $96 million with Maverick has come under scrutiny by The Houston Chronicle and other publications, which focused attention on the possibility that the placement resulted from Wyly family contributions to Mr. Bush. Mr. Bush, as well as officials of the school's management group and Maverick, have denied such suggestions.

Some of Mr. Wyly's business practices, however, have come under fire. In 1979, he settled S.E.C. charges that he made undisclosed payments to associates to buy up company bonds as part of a plan to stave off bankruptcy. He settled without acknowledging any wrongdoing.

In 1998, the California Public Employees Retirement System, or Calpers, described Michaels Stores, at which Mr. Wyly serves as chairman, as having some of the "most egregious corporate governance practices" of any publicly traded company.

In particular, Calpers pointed to decisions by directors of the company board, which it described as "dominated by Wyly family" interests, to award themselves and corporate executives overly lucrative compensation packages and generous golden parachutes. Those directors also repriced their stock options to benefit themselves during years when the company's stock was low, Calpers said.

"We find it difficult to accept that these actions are representative of an independent board," Charles P. Valdes, chairman of Calpers' investment committee, said in 1998.

In response to Calpers' concerns, Mr. Wyly said that Michaels Stores had since appointed two independent directors. "We have met with Calpers," he said, "and I think they are happy today with what we are doing."

A spokesman for Calpers, Brad Pacheco, said the pension fund was pleased with the changes but still had questions about the company's performance.

Mr. Wyly, his son, Evan, and his daughter, Lisa, as well as offshore trusts whose beneficiaries are Wyly family members, also hold stakes in GreenMountain.com, S.E.C. filings show. Those documents also show that Maverick Capital invested $15 million in GreenMountain.com immediately before last year's planned stock offering.

Nothing barred such an investment. But the move is striking given previous comments by Lee S. Ainslie III, a Maverick managing partner, that the fund would not invest in a Wyly-controlled company. Evan Wyly is the fund's other managing partner, said Sam Wyly, and Wyly family investments make up about $400 million, or 10 percent, of the fund's assets.

"We work very hard to maintain a degree of separation between the entities," Mr. Ainslie told Barron's in 1996. "For instance, we never have and we never will be able to have any stake -- we being Maverick -- in Sterling Software or Michaels Stores, just because there's too much potential for conflict of interest."

Mr. Ainslie said Maverick's investment in GreenMountain.com, which first took place in 1997, was not at odds with his previous comments because the energy concern is a private company.

"There has been no change to our policy of not making an investment in public companies where we believe there is potential for a conflict of interest that would result from nonpublic information," said Mr. Ainslie, who added that he was in charge of the fund's investments.

S.E.C. documents show that if the planned stock offering by GreenMountain.com had gone forward, Maverick Capital would have retained an 11 percent stake in the company.

Maverick Capital also holds a 9 percent stake in Scottish Annuity and Life Holdings, a publicly traded insurer based in the Cayman Islands. Until last month, Mr. Wyly was chairman of the company.

Mr. Ainslie said that at the time Maverick's investment was made, Scottish Annuity was also a private company. S.E.C. filings show that a major investment by the fund was made one month before the insurer's initial public stock offering in 1998.

Mr. Wyly said he did not see any conflicts with Maverick Capital's investment in GreenMountain.com. David Russ, managing director of public markets for the University of Texas Management Investment Company, said the group's guidelines did not bar Maverick from investing in the energy company.

Mr. Wyly said he had no immediate plans to pay for ads against Vice President Al Gore during the general election, but Mr. Wyly added that he and another son, Andrew, a Dennison University student whom he credits with the promotions against Mr. McCain, have kicked around ideas.

They would be built around the theme that Mr. Gore, whose environmental record might appeal to some voters, was a regulation-happy Democrat who would not be good for business or the environment.

"Be green without being red," said Mr. Wyly, testing out a slogan on a listener. "Al Gore is an heir to the old czars and commissars. He never saw a regulation he didn't like."

CORRECTION:
A picture caption in Business Day on Thursday with an article about Sam Wyly, the Texas investor and Republican campaign donor, misidentified the target of criticism of his management practices and those of his associates. It has focused on public companies in which Mr. Wyly and his family have interests. It has not extended to Maverick Capital, a private hedge fund that Mr. Wyly founded.

GRAPHIC: Photos: Sam Wyly poses in front of a portrait of himself at his Dallas home. Mr. Wyly, a financial backer of George W. Bush, is chairman of GreenMountain.com, which markets alternative energy sources like solar power and wind power through its Web site. He is also a founder of the $4 billion hedge fund, Maverick Capital. Critics say the decisions of his management teams at Maverick Capital and other companies have sometimes benefited Mr. Wyly's family members more than shareholders. (Mark Graham for The New York Times)