U.S. regulators on Friday suspended trading in Cynk Technology Corp, citing possible market manipulation in the one-time penny stock whose market value rocketed within weeks from less than $20 million to more than $6 billion.

After the virtually unknown company with no assets or revenue skyrocketed in value for no apparent reason, the Securities and Exchange Commission and Financial Industry Regulation Authority(FINRA) decided to pull the plug. Listing its business address in Belize but filing out of Nevada, the company said it intended to create a social network business.

FINRA posted a trading suspension in the stock early on Friday using its "Extraordinary Event Halt" code. The SEC followed with its own suspension shortly afterward, extending the trading hiatus until July 24.

The SEC cited "concerns regarding the accuracy and adequacy of information in the marketplace and potentially manipulative transactions in Cynk's common stock."

Shares of Cynk, a development-stage company which SEC filings said formerly went by the name Introbuzz, were hardly ever traded, exchanging hands at pennies per share through late May. Beginning on June 17, shares rocketed from 6 cents to as much as $21.95 at one point on Thursday.

Based on Thursday's closing price of $13.90, its stock market value is $4.05 billion. At its peak, the stock had a higher market value than three dozen members of the S&P 500 including Cablevision Systems Corp, Pitney Bowes Inc, Legg Mason Inc and ADT Corp.

Identified in regulatory filings as a Nevada corporation, it has a business address in Belize City, Belize. Financial statements with the SEC show no assets, no sales and no positive cash flow. Its last quarterly report, from the third quarter of 2013, shows a net loss of $11,275 for the period.

Its website, site.introbiz.com, lists no phone number. A form for contacting the support group warns that it could take two days to respond.

An investor named Marlon Sanchez was listed as owning 72 percent of the 291 million outstanding shares. But he had sold his stake, according to a June 11 letter to OTC Markets Group Inc, operator of the OTC Pink market on which Cynk shares traded.

The letter, signed by a Las Vegas attorney Harold Gewerter, described Javier Romero, a resident of Belize, as the "sole officer and director" of Cynk.

The document, posted on an OTC website, said Romero has owned 210 million shares, roughly the same 72 percent of outstanding shares, since Feb. 20, 2014, "which he purchased from the former sole officer and director" - Sanchez.

But SEC filings dated after that point continue to identify Sanchez as the company's president and chief executive officer.

In March, identifying himself as president and CEO, Sanchez signed a filing with the SEC indicating Cynk's inability to file its 2013 annual report on time.

Sanchez is again shown as the company's president and CEO in an April 10 filing, a Form 15, used by listed companies to either revoke the registration of securities or to notify the SEC of the company's plans to stop filing various forms. That is the last filing with the SEC from Cynk.

Calls to the phone number listed in that filing reached an automated recording saying: "You have reached an unassigned number."

Sanchez disclosed in an April 2013 filing to the SEC for Introbuzz that he graduated from San Diego State University with a degree in Business Administration Marketing. An alumni official said Sanchez was not in the university's alumni data base.

Regus, the company that rents out space in the business center in Las Vegas where Cynk had its offices, said a company named Introbuzz had offices there through the end of June but no longer operates in the building.

Regus would not elaborate on how long Introbuzz had the offices, or why it had left.

The attorney, Gewerter, responded to Reuters with an email saying he no longer represented the company.

OTC Markets did not immediately return a call for comment.

VOLUME SPIKE

Before June 17, Cynk shares had traded on three days in 2014, with daily volume not exceeding 2,000 shares. Trades had occurred at either 8 cents a share or 6 cents, its closing price on May 15, when it last recorded trades before mid-June.

Then, activity in the stock exploded.

Volume on June 17 topped 367,000 shares and the price shot to as high as $4.25, before closing the day at $2.25. Trading on every day since then averaged 120,533 shares. The price soared.

The frenzy culminated on Thursday with a record volume of 386,060. The share price spiked as high as $21.95 before closing at $13.90, down from Wednesday's close of $14.71.

The SEC suspension is valid through July 24, but no quotation may be entered after that date unless brokers and dealers have complied with all rule provisions, the SEC said in a statement, which could effectively extend the suspension.

The SEC has suspended trading in more than 1,300 micro-cap stocks since May 2012, said Eric Bustillo, regional director of the SEC's Miami Regional Office, who declined to comment specifically on the Cynk suspension.

He said since last year, the SEC has been "placing significant emphasis and resources" on micro-caps as it is "an area that we have seen significant fraud in." 

(By Rodrigo Campos; Additional reporting by Chuck Mikolajczak in New York, Alexandra Alper in Mexico City and Sarah N. Lynch in Washington D.C.; Editing by Bernadette Baum, Dan Burns and David Gregorio)