Milestones, milestones.

The Net sector rallied sharply Thursday, as tech investors cheered the

Nasdaq Composite Index

to its first close above the all-important 5000 mark and merger partners

VeriSign

(VRSN) - Get Report

and

Network Solutions

(NSOL)

made up lost ground on their breakthrough e-commerce pact.

TheStreet.com Internet Sector

index jumped 45, or 3%, to close at 1333. The Nasdaq closed up 149, or 3%, at 5047, barely two months after it

breached the

magical 4000 barrier Dec. 29, 1999.

Network Solutions leaped 71 1/16, or 17%, to 494 1/2 after reaching an intraday high of 504 7/8, and VeriSign jumped 37 3/4, or 17%, to close at 240 3/4. VeriSign shares had fallen sharply since the Internet security concern agreed Tuesday to join Internet registry outfit Network Solutions in a deal now valued at around $20 billion. But Thursday's action saw VeriSign recapture almost all its lost ground, while Network Solutions continued the strong uptrend it has seen on the heels of the deal.

Investors

reacted strongly to the deal when it was announced Tuesday, but analysts say management teams for both companies have been visiting investors in New York and Denver, and today's stock action shows that investors are starting to understand the logic behind the pairing of VeriSign's Net security firm and Network Solutions' domain name registry business. The Street "is seeing that this is a very powerful combination," says Todd Weller, a B2B e-commerce analyst with

Legg Mason

. Weller has an outperform rating on Network Solutions and has had no underwriting relationship with the company.

Read On! There's More!

America Online

(AOL)

, buoyed by a

Bloomberg

report that CEO Steve Case is continuing talks with

AT&T

(T) - Get Report

about forming a partnership, closed up 5 15/16, or 11%, at 37 3/4, after reaching an intraday high of 61.

Ariba

(ARBA)

, which rose Wednesday on news of an alliance with fellow B2B star

i2 Technologies

(ITWO)

and

IBM

(IBM) - Get Report

, gave up ground Thursday, slipping 10 1/8, or 3%, to 320 7/8. i2 Technologies jumped 30 1/4, or 16%, to 220 7/8, and IBM added 1 3/8, or 1%, to 107 5/8.

RealNetworks

(RNWK) - Get Report

added 9 13/16, or 14%, to 80 3/4 after

Wedbush Morgan

started the stock at strong buy.

Software.com

(SWCM)

, a developer of Internet infrastructure applications, closed up 32 11/16, or 29%, at 146 13/16, after saying it would buy

@mobile.com

for $400 million in stock.

Pets.com

(IPET)

, the online pet retailer that has languished since its Feb. 11 IPO, closed up 1 1/2, or 21%, at 8 17/32, after

Warburg Dillon Read

started coverage with a buy rating and a 20 price target.

Not wanting to miss out on the fun, Net bellwethers

Amazon.com

(AMZN) - Get Report

and

Yahoo!

(YHOO)

rallied as well: Yahoo! added 6 1/4, or 4%, to close at 183 1/4, while Amazon closed up 5 3/16, or 8%, at 68 13/16.