I.P.O.'s Face Road Blocks as Markets Turn Shaky One is a former Home Depot division that serves construction and maintenance contractors, while the other is a leading video advertising network. But the market turmoil of recent weeks may have made both companies" planned initial public offerings a bit bumpier all the same. HD Supply priced its stock sale at $18 a share late Wednesday, well below its expected range. Tremor priced its offering at $10 a share, below an anticipated range of $11 to $13, according to a person briefed on the matter who spoke on the condition of anonymity because the discussions were private. The CDW Corporation, a technology products retailer, priced its stock at $17, the low end of an already-reduced range. Their fortunes illustrate the sometimes rocky path for companies seeking to go public this year as once ebullient markets have had an occasional bout of shakiness, driven largely by concern that the Federal Reserve will soon begin pulling back on its economic stimulus. In January, Pfizer exceeded expectations when it spun off its animal health unit at a higher-than-expected price, raising $2.2 billion. The stock markets then were climbing with little sign of a slowdown. But recent jolts in the stock and bond markets have reintroduced some caution into Wall Street, with the Standard & Poor's 500-stock index down nearly 3 percent over the last month. That has prompted some investors in I.P.O."s, which are some of the riskiest equity deals around, to push for better terms from sellers and underwriters. "What we've been seeing are deals that are being reconfigured," said David Menlow, the president of IPOfinancial.com, a research firm. Some companies will be able to endure such a process, while others won't. One group likely to face difficulty in the current environment are companies owned by private equity firms, which are eager to sell holdings to earn profits from their investments. Many of them took on significant amounts of debt in their takeovers, especially those struck at the height of the credit boom in 2007. Both HD Supply and CDW disclosed that the proceeds of the stock sales were aimed primarily to pay down their obligations. Those heavy burdens may have prompted investors to demand better terms for their money. That led to HD Supply raising $957.6 million in its offering, a less-than-expected haul to reduce the company's $6.6 billion in debt. The company had hoped to seize upon expectations of a revival in the construction industry. HD Supply reported a 16.7 percent gain in net sales for its second quarter, to $2.1 billion, and a 65 percent cut in its net loss, to $131 million. The architects of the company's $8.5 billion leveraged buyout - the Carlyle Group, Bain Capital and Clayton Dubilier & Rice - are not selling their holdings and will still own about 57 percent of the company after the I.P.O. CDW, too, was forced to lower its expectations. Its primary owners, the private equity firms Madison Dearborn and Providence Equity Partners, abandoned plans to sell some of their holdings, leading to a smaller-than-expected $396.1 million in proceeds from the offering. Market pressures appear to have weighed on Tremor Video's debut, though the company's offering is significantly oversubscribed, according to the person briefed on the matter. The online ad network raised $75 million in its closely watched offering, potentially setting a precedent for a slew of other advertising technology offerings poised to come to market. Founded in 2005, Tremor focuses on putting ads into videos instead of in separate banners on sites. For its second quarter, Tremor reported a 43 percent revenue gain from the year-ago period, to $24.8 million, and a near-halving of its net loss, to $5.2 million.