The stock of Nextel Communications Inc., hit an all-time high of $91.43 3/4 a share yesterday after the Reston mobile telephone company completed the high-finance equivalent of a hat trick.

Nextel over the past two weeks has put together a multibillion-dollar war chest through stocks, bonds and credit lines that will permit it to pay off debt, expand its networks to keep up with exploding demand for wireless phones and--most important--make acquisitions.

Nextel negotiated a new $5 billion credit line, raised $2.4 billion in a stock offering and picked up an additional $2 billion in the bond market.

Nextel sketched out some of its plans for using the money in stock offering documents, which cited the rapid growth in mobile phone use in the last year. Company officials yesterday provided few new details, noting that a bankruptcy court has imposed a gag order on their top potential acquisition and that the Securities and Exchange Commission restrict comments during stock offerings.

Controlled by cellular phone magnate Craig McCaw, Nextel operates a nationwide mobile phone network catering to business customers.

While the Federal Communications Commission set aside special radio frequencies for cellular phone use, Nextel found a way to offer a competing service using a collection of radio bands that previously had other uses. Once regarded as an oddball competitor to conventional cell phones, Nextel has become a major player by methodically picking up frequencies in regions throughout the country.

The cache of cash should give Nextel more than enough money to make the big purchase it has been pursuing--a trove of idle airwaves controlled by NextWave Personal Communications Inc., now in bankruptcy proceedings.

NextWave made the winning bids when the radio frequencies were auctioned off by the FCC in 1996 but sought bankruptcy protection when it could not come up with $4.7 billion to close the sale.

Because of the gag order, Nextel officials declined to confirm reports that its lawyers have told the bankruptcy court it would be willing to pay as much as $6 billion for the airwaves.

Nextel's bankers took out big newspaper ads yesterday to proclaim that last week's sale of 30 million shares of stock at $83.81 1/4 a share was "the largest primary offering for a U.S. public company"--an honor that Nextel immediately lost to United Parcel Service of America Inc.

UPS went public yesterday, raising $5.5 billion in an initial public stock offering that eclipsed the previous record $4 billion IPO of Conoco Inc.

The Conoco deal, however, was a spinoff from DuPont Co. that didn't qualify as a "primary offering" as that term is used by Nextel and its investment banking team, led by Morgan Stanley Dean Witter and Goldman Sachs Group Inc. They define primary offering as the sale by a company of its own stock--either in an IPO or a follow-on offering--to raise capital for its own use.

Like its competitors, Nextel has borrowed heavily but recently decided to take advantage of a spectacular run-up in its stock price--which has jumped 287 percent since last New Year's Eve, when it was at $23.62 1/2.

When plans for the big stock offering were announced last month, Nextel shares dropped $13 in a couple of days--a typical reaction to an impending offering. Selling more shares dilutes the interests of existing shareholders, but the impact on Nextel stockholders was dismissed as "pretty insignificant" by analyst Peter Friedland of ING Barings.

By the time the stock offering hit the market Nov. 2, Nextel stock was back within a couple dollars of its price before the offering was disclosed. And in another sign of investors' confidence, the size of the sale was boosted from 25 million shares to 30 million shares.

The new shares began trading last Friday, just as Nextel took advantage of a lull in the junk bond market to raise another $2 billion. Advised by its investment bankers that investors were eager for bonds, but there were few new issues coming up for sale, Nextel cooked up the offering in 24 hours. The 10-year notes, which pay 9.375 percent interest, were sold to institutions in a private placement, avoiding the delays and paperwork of a public offering.

In the midst of those two transactions, Nextel also renegotiated its credit lines with banks and other lenders who agreed to raise the company's credit line from $3.3 billion to $5 billion.