International Automated Systems Inc. shares plunged as much as 75 percent after the company failed to deliver a long-promised demonstration of its new telecommunications technology.

International Automated's shares fell 20 points, or 50 percent, to 20 in midafternoon trading of 98,500 shares. The tiny company's market value registered a one-day decline of $489 million earlier, when its shares plunged to 10.The stock, which traded at 31/4 last July, touched a record high of 57 on May 24. At that price, the market valued the company, which has 16.3 million shares outstanding, at $929.1 million.

International Automated has run newspaper advertisements for months promising to introduce its new "digital wave modulation" technology on June 27. The company said its DWM technology "will spearhead a revolution" in communications, saying it is nearly 200 times faster than today's modems in transmitting information.

In its ads, the company said the technology "redefines the boundaries of science."

In a June 12 ad in Investor's Business Daily, International Automated said it would "unveil its operational DWM prototype" last week.

A recent unveiling at company headquarters in American Fork, Utah, included 21/2 hours of speeches by company executives, but the promised demonstration of the technology never happened.

"We didn't actually have a working prototype, but our technology does work and we are for real," said David Snow, a company spokesman. He said company president and chief inventor Neldon Johnson did "unveil" the technology in a 45-minute lecture.

"There were people there expecting something they could hold in their hand," Snow said. "We weren't able to produce that." He said the company still expects to demonstrate a prototype "in the very near future." The company hasn't released a written explanation of the technology, Snow said.

Meanwhile, the 10-year-old company, which has 15 employees and no profits, has never filed a financial report with the Securities and Exchange Commission. It's never had to.

An exemption designed to ease red tape for small businesses that want to raise money has a flip side: depriving investors of financial information about thousands of public companies, such as Internat- ional Automated, which are traded on the OTC Bulletin Board.

The company lost $199,554 on revenue of $6,000 for the year ending June 30, 1995, according documents provided by the company. Its assets totaled $53,226, and it had a negative net worth of $128,558 as of that date.

On Dec. 13, its auditor warned that "the company may be unable to continue in existence." Yet even at a price of 20, the company has a total market value of $326 million.

To be sure, the company's claim to "revolutionary" technology has drawn skeptics, as reported by Bloomberg Business News May 10, when the stock traded at 36.

"Chutzpah is alive and well in American Fork," said telecommunications analyst Rob Rich of the Yankee Group in Boston at that time. "I'll believe it when I see it."

In advertisements touting its stock, the company thumbed its nose at non-believers like Rich while promoting the unveiling of its technology.

"We have enjoyed creative insults directed at us by skeptics," said an ad that ran in April. "We encourage those of you who have missed the opportunity to ridicule us to hurry - you only have about two more months."

Skeptics like Rich now have been granted a little more time.