The world of options trading is known for springing leaks, with puts and calls bouncing on news that hasn't yet hit the larger market.

Lately, though, put and call options have been moving on rumors circulating in the market, but underlying stocks haven't. When stocks have poor volume patterns and the key clue -- implied volatility -- isn't rising, "that's often a sign that 'big' money is not playing. That's the kind of rumor that collapses quickly," said Lawrence McMillan of

McMillan Analysis

.

One example he cited was the Tuesday whispering that

NetGravity

(NETG)

was a takeover target of

DoubleClick

(DCLK)

.

NetGravity's stock has broken out above a technical base of 23 but has poor volume, and implied volatility is actually down, he noted.

Onsale

(ONSL)

is also a rumored takeover target by

Amazon.com

(AMZN) - Get Report

but is "too overbought to chase," McMillan said.

The key to the life of these rumors is the foundation of the guess.

Take note of the common sense of these rumored outcomes, said Seth Washburne of

Washburne Capital Management

, a merger-arbitrage hedge fund investing in takeover deals.

For instance, in the case of NetGravity, DoubleClick has laid out for several other purchases recently, and "while sometimes companies go out and buy three different businesses at the same time, buying on rumors can really be a zero-sum game," he said.

Another option spinning in the rumor mill is

Metricom

(MCOM)

. The company's call options continued to march higher, with prices up in nearly every strike price. As the stock raced up 6 5/8 to 34 3/8 by midday, the July 30 calls were up 2 3/16 ($218.75) to 4 7/8 ($487.50).

There was no news on the company, other than continued positive sentiment about the investment in Metricom by Paul Allen's

Vulcan Ventures

and

MCI WorldCom

(WCOM)

.

Other than tech favorites,

Becton Dickinson

(BDX) - Get Report

, a medical supplies and diagnostic products company, was among the most actively traded options.

Roughly 2,025 August 30 call options crossed early in the trading session, with the price up 13/16 ($81.25) to 1 13/16 ($182.25) against open interest of just 86 contracts. Becton Dickinson's stock, meanwhile, was up 7/16 to 29 3/8.