Like its predecessors, the latest installment in the wildly popular "Harry Potter" series should wave at least a small magic wand over the bottom line of the book's publisher, Scholastic.

But the financial impact of the newest yarn about the young wizard, "Harry Potter and the Half-Blood Prince," will likely be modest rather than miraculous. That's because "Potter" sales account for a relatively small portion of Scholastic's revenue. The No. 1 children's book publisher is a vast, $2 billion company that has grappled with a lukewarm retail book market and glitches in other units.

"Harry Potter" is very profitable and very important to the Scholastic franchise, but it's not the main driver of the company, says Goldman Sachs analyst Peter Appert.

"Harry Potter and the Half-Blood Prince" broke sales records over the weekend, with 6.9 million copies of the series' sixth book flying off U.S. shelves in the first 24 hours. After an initial printing of 10.8 million, Scholastic rushed an additional 2.7 million into print.

"We are ecstatic," says Lisa Holton, head of Scholastic's children's book division.

Still, the bang-up opening weekend is not prompting Appert to change his forecast. "Half-Blood," he predicts, will sell 12.5 million copies and generate $175 million, or 7.4 percent of Scholastic's revenue and 20 percent of its profit in fiscal 2006. That's down from 2001, when "Potter" yielded 33 percent of profit, partly because series author J.K. Rowling now commands royalties of 12 percent of sales or higher, Appert says.

Scholastic transformed publishing by turning "Potter" opening weekends into marketing events akin to blockbuster movie releases. "It's like one big party," Holton says.

But as with much-hyped films, Appert says, sales will likely even out the rest of the year.

The company was founded in 1920 by M.R. "Robbie" Robinson, the father of current CEO Dick Robinson. It initially sold magazines to schools. Today, Scholastic owns virtually the entire market for school-based book clubs and fairs. It also sells course materials, videos, toys and computer products.

Yet publisher revenue for books sold at retail has been growing at just 2.9 percent a year. Also, after buying a company that markets book-club memberships to parents, Scholastic stumbled. It did not anticipate the high number of customer returns and nonpayments, Appert says. Profit in fiscal 2004, ended May 31, was flat at $58 million.

The company largely ironed out the wrinkles. Appert projects revenue of $65 million in fiscal 2005 — for which the company plans to report results Wednesday — and $98.7 million in fiscal 2006.

Sales of "Half-Blood" may not be reason enough to buy Scholastic stock. Investors "will continue to be wooed" by the "Harry Potter "franchise, but the stock is pricey at $37.34, and attention is shifting to Scholastic's "core business," says Prudential Equity Group analyst Steve Barlow.