Move over, Brooks Brothers. Wall Street is headed to Banana Republic and the Gap.

Almost as fast as digits change on the ticker these days, the banking uniform of dark suit, dress shirt and lace shoes is being dumped like a gravity stock in favor of chinos, denim shirts and loafers.

At first, it was casual just on Friday’s.

But last month, J.P. Morgan went casual every day of the week. Goldman Sachs followed suit last week, and Merrill Lynch has gone casual every day, too, except for its headquarters staff.

Now the rest of the stuffy finance-house gang — Morgan Stanley Dean Witter, Lehman Brothers, Bear Stearns and Donaldson Lufkin & Jenrette — are said to be on the verge of embracing khakis and twin sets.

Not surprisingly, most men on Wall Street are overjoyed to trade in their uniforms of Brook Brothers suits, Hermes ties and Turnbull & Asser shirts for much more comfortable gear.

“I get up a whole half-hour later in the morning,” boasts J.P. Morgan information-systems specialist Peter Coffy, 27, who looks like a walking billboard for J. Crew in his blue shirt and khaki pants. “My dry-cleaning bills? They’re next to nothing now.”

“It’s definitely harder to figure out what to wear in the morning, and sometimes I wonder if my office mates will do a double-take on what I pick out,” frets J.P. Morganite David Sewell, 32, who’s decked out in a rumpled Barney-the-dinosaur-purple shirt paired with a forest-green blazer.

“But you don’t have to worry about wrinkled suits while traveling–you just shove stuff in your bag and wear it the next day. I think rumples give my clothes character.”

But the boon for men is a problem for women who feel naked stripped of their power suits.

“I normally try to wear a suit Monday through Thursday,” says Christie Morgan, 28, a recent recruit to J.P. Morgan who was wearing a burgundy sweater and black slacks when she talked to The Post.

“You’re catching me on an off day,” she explains.

“When I put on a suit, I feel like I’m dressing up. It makes me stronger, more self-confident, more able to deal with anything. If I had to handle a crisis, I’m not sure I would respond as well in casual wear.”

Some women also complain that fashion and finance have never been known as a formula for Wall Street success.

“There was a lot of excitement at first among some of the guys — (-ssq-)Oh, yeah, the women are going to start wearing short skirts and tight tops’ — which just seemed ludicrous,” says one Wall Street vice-president who says her wardrobe staples now are slacks and cashmere sweaters.

“I need my clients to respect me and see me as a figure of authority — I don’t want to wear anything that could lead them to view me differently.

“I think over the past year, women have moved from suits to jackets and skirts to jackets and pants. Now we’ve just moved down another notch, to something more casual, like the sweater set.”

“I wouldn’t wear any of the animal prints or bold colors the stores are showing for spring,” adds Diane Oldja, 28, who works in the equity-research department at J.P. Morgan.

“Morgan’s a conservative place — you don’t want to give the wrong impression. I’m essentially wearing the same clothes, minus the blazers and blouses. I just pair my skirts and pants with twin sets or turtlenecks.”

But not every woman downtown is as loathe to buy into the casual bounce as Oldja and Morgan.

“I’m a big fan of casual wear,” says banker Salena Dabbs, 27. “It makes me feel better, more dominant, more together. Not having to worry about getting all gussied up leaves my mind free to deal with more important things — like my job.”

And there are many — both women and men — who insist the new dress code is helping them develop a sense of personal style.

“I definitely would not have worn this before,” says consultant Gordon Henwood, proudly showing off his bright-orange sweater.

“But hey, I think it lets me show my own unique character. It’s who I am, you know?”

Cynics say the move to casuals on Wall Street has very little to do with fashion and a lot to do with competing with business and for the best recruits.

White-shoe institutions like J.P. Morgan and Goldman Sachs have recently found themselves at a disadvantage competing with the laid-back dot-com companies for the pick of the MBA crop.

“Sixty percent of Ivy League MBAs used to go to the top Wall Street banks,” says dot-com consultant Nathan Duncan.

“Now it’s closer to 35 percent. The best and brightest are going to the Internet startups because they can make the same money as on Wall Street without the lifestyle sacrifices.

“Wall Street bankers are trying to soften their image with younger recruits — to loosen up a bit.”

But for some uptight Wall Streeters, the casual-dress momentum is just another source of stress.

“I didn’t have any clean casual clothes left to wear to work,” said glum banker Brian Shay, 26, who looks uncomfortable and out of place in his navy-blue suit. “Who has time to do laundry?”

A brain wave hits, and he brightens up:

“Maybe I’ll spearhead a whole new trend — and suits will come back.”