CHICAGO (Reuters) - Holders of thousands of August stock options on cash-strapped satellite telecommunications company Iridium LLC were scrambling Friday to figure out whether they could profit or get hurt by exercising their expiring options.

The same day, the Nasdaq market halted trading in the stock, which last sold at 3-1/16. All four U.S. options marts also stopped trading in options, which had strike prices ranging from 5 to 20 for the August expiration but as high as 40 in the deferred months.

Since then, the stock has not traded, but time continued to march toward Friday afternoon's 1630 CDT/2130 GMT deadline for holders of the more than 32,800 August puts and near 26,900 calls to decide about exercising their options to buy or sell the stock, whenever it reopens for trading.

Market players holding options to buy or sell Iridium shares at various prices must now guess whether Iridium shares will open higher or lower when they are finally cleared to trade again.

The seller, or grantor, of the option must buy the underlying stock from, or sell it to, the option holder if the holder chooses.

``The only alternative left for the people who hold the options...is whether to exercise or not,'' said Thomas Stotts, managing director of options trading at Dain Rauscher Wessels. ``The questions is: What does it (bankruptcy filing) mean for the price of the stock when the stock reopens. At least part of the time, it has a positive short-term reaction.''

Near-the-money August 5 calls -- which give its holder the right to buy the underlying stock at a predetermined ``strike'' price -- had open interest of 9,096. At the same time, 9,268 August 5 puts -- which give buyers the right to sell the stock at the strike price -- remained open Friday afternoon.

Open interest figures show the number of outstanding contracts for a given option which are not offset by an opposing transaction or fulfilled by delivery.

Normally, when an option is ``in-the-money,'' entitling the holder to take a long or short position in the underlying stock at a better price that the prevailing market, those valuable options are automatically exercised by the trader's clearing firm for a tiny fee, explained Lynn Howard, spokeswoman at the Chicago Board Options Exchange.

But in this case, which is unusual but not unique, any option owner who wants to exercise into the stock must submit a form to the clearing firm instructing it to exercise.

``There is no automatic exercise,'' said Howard. ``Nobody knows where the stock is, so you have to decide.''

``Actually, everybody's thinking the stock's going to open lower, like at a buck,'' said an options source. ``But it's anybody's guess.''

``It's a valid issue,'' said an options strategist. ``The puts might be worth something.''

``The bad part is the people (grantors) who are short them are kind of helpless,'' added Stotts. ``They don't have any alternative here.''