NEW YORK (CNN/Money) - Michael Dell and Steve Ballmer each has taken some money off the tech table. Should you?

The CEOs of Dell Computer and Microsoft (MSFT: Research, Estimates) made headlines in the past two weeks for selling rather large portions of stock. Dell has sold 10 million shares worth about $300 million. Ballmer has sold about 60 million shares for $1.5 billion.

To be sure, the two CEOs still own a substantial amount of stock in their companies. And such sales aren't necessarily a sign of impending doom.

Lon Gerber, director of insider research for Thomson Financial, says that such big sales are usually a matter of diversification and not a good predictor of stock performance.

But the Nasdaq is up more 27 percent since March 11. And one research firm that closely follows insider transactions said that more tech insiders have been selling during the rally and that the average investor should lock in some gains if possible as well.

Michael Painchaud, director of research and principal of Market Profile Theorems, said that based on a recent pickup in insider sales, he is recommending a "neutral" rating on the tech sector for the first time since last July.

Tech sell-off The following five tech execs have taken advantage of the sector's rally. Company  Insider Name (Title)  Date of sale(s)  # of shares sold  Selling price range  Microsoft   Steve Ballmer (CEO)  5/21-5/30  59.9 million  $23.89-$24.90  Dell Computer  Michael Dell (Chairman & CEO)  5/22-5/27  10 million  $29.56-$30.01  Cisco Systems  Larry Carter (Former CFO)  5/22  625,000  $15.98  Priceline.com  Richard Braddock (Director and former CEO)  5/5-5/6  1 million  $3.16-$3.17  Network Appliance  Daniel Warmenhoven (CEO)  5/23  100,000  $15.29   Sources: Edgar Online, EdgarPro

In addition to Dell (DELL: Research, Estimates), which also saw option-related insider sales last week by COO Kevin Rollins and CFO James Schneider, Painchaud pointed out that Cisco Systems (CSCO: Research, Estimates), Priceline.com (PCLN: Research, Estimates) and storage hardware company Network Appliance (NTAP: Research, Estimates) have had some notable insider sales in the past month.

Former Cisco CFO Larry Cater, who retired last month, sold 625,000 shares in May. The stock is up 26 percent since March 11.

Priceline.com is up nearly 220 percent since March 11 and last month, five insiders sold nearly 2 million shares. Director and former CEO Richard Braddock sold 1 million shares.

Five Network Appliance insiders sold shares last month, including CEO Daniel Warmenhoven, who sold 100,000 shares. The stock is up more than 80 percent since March 11.

But Painchaud said that the increase in selling is not necessarily a bearish sign. He calculates a 1-10 score for sectors based on several factors, including the dollar amount of insider sales, the ratio of sells to buys and whether sales are options related. The rating for the tech sector now is a 3, which is line with its historical average.

This rating is higher now than when it was in 2000 and 2001, when it was closer to 1. So Painchaud simply thinks that after such a big rally for the group, it might be difficult for the sector to continue to outperform and that insiders realize this as well.

"Things are now back to normal and that's a pretty good summation of the behavior of tech insiders lately," said Painchaud. "The tide is now going out."

The increase in insider selling is not unique to tech, either. Overall, insider sales in May are on track to be the highest in two years, according to Thomson Financial. The figures are not final since insiders that sold late last week would not have to file until the middle of this week.

More about insider selling Ballmer sells more shares Ballmer sells stock worth $1.2 billion Tech insiders: Nobody's buying

Thomson's Gerber said sales by tech company insiders represented about 20 percent of the monthly total, which is about average for the group. "It's clearly up over prior months but it isn't an astronomical increase," Gerber said.

In other words, tech insiders aren't heading for the exits. But it appears that they are wise enough to recognize a profit-taking opportunity when they see it.