The company that makes the BlackBerry has a short window to revive its sagging share price and shake up its business, or risk the escalation of a dissent movement that claims support from holders of 8 percent of its stock.

Three Research In Motion shareholders backing a call from merchant bank Jaguar Financial for transformational change at the Canadian smartphone company said the still-informal group was bound to grow if RIM's shares don't rebound soon.

I would say that if we are still looking at this stock in this position by the middle of next year then I think there will be a lot more support than just 8 percent, one of the shareholders told Reuters. He said he was not ready to be identified because he did not want to go public with his investment strategy.

Jaguar says the dissidents want a sale of the company as a whole or in parts, and the replacement of co-CEOs Mike Lazaridis and Jim Balsillie. The pair are RIM's two largest shareholders and the most powerful figures in its management.

The discontent centers on the BlackBerry maker's poor performance in the face of stiff competition from Apple Inc's iPhone and IPad, and devices powered by Google's Android system. Its stock touched a six-year low of $18.77 last week after figures showed its share of the lucrative U.S. smartphone market had slumped to 9 percent in the third quarter from 24 percent a year earlier.

Shareholders who back Jaguar said they want to see a share price that is at least in the $40-$60 range. On February 18 it hit a year-high of $70.54 on the Nasdaq.

Our valuation is substantially higher than here, certainly north of $50, said one of the dissident shareholder.

Jaguar says none of the members of Jaguar's informal group know who the others are, and there is no concerted action or decision-making by the group at this point. They are united only by independent conversations with Jaguar, it says.

Jaguar Chief Executive Vic Alboini says there are 13 shareholders in his camp, but he declined to identify them.

There is no collaboration on RIM other than, 'we support the Jaguar initiative to cause corporate governance change, and to push the company to put itself up for sale or pursue strategic options', Alboini said.

The point he makes is important because a group of shareholders acting together and holding at least 10 percent of shares is obliged by law to disclose its membership.

Jaguar has a history of targeting underperforming companies. In 2009, Alboini played a crucial role in scuttling HudBay Mineral's friendly bid for Lundin Mining, successfully appealing the Toronto Stock Exchange's approval of the transaction.

THE QNX ALTERNATIVE

In separate conversations with Reuters, the three shareholders said they backed Jaguar because it seeks change, although they don't see the company shake-up advocated by Jaguar as the only possible route.

All hope RIM can turn its stock price around in coming months as it deploys its new QNX software on handheld devices.

RIM is counting on the souped-up operating software to help it regain ground lost to Apple and Google. But the company has not yet said when it will expand the use of the new platform, Right now it is only used to power RIM's poorly received PlayBook tablet computer.

My concern with RIM as a shareholder is the following: they need to step up the pace of getting the word out on what they are doing, said a second shareholder who backs Jaguar. I'm behind Jaguar as a way to put the spotlight on this.

A third investor indicated his company might be willing to go public about its support for Jaguar's demands at a later date if RIM fails to revive its stock price.

They are on a short leash at this point, the investor said. If their Plan A isn't working then we apply pressure.

Alboini said he has tried to speak to the RIM board but has been rebuffed so far.

He said the group has held off on demanding an open RIM shareholders meeting, their right as holders of more than 5 percent of the stock. Such a request would require members to reveal their identities as a formal group.

We're waiting to see if we can do this in a friendly, logical, methodical manner, and so far we've been unsuccessful, but we're going to keep plugging away, he said. This is not a sprint. This is a marathon and we have to play our cards right.

(Reporting by Pav Jordan and Alastair Sharp in Toronto; editing by Janet Guttsman and Frank McGurty)