Here are Thursday’s biggest percentage gainers and losers, along with top volume leaders, among companies with a market cap between $50 million and $750 million:

Biggest percentage gainers:

• R.H. Donnelley Corp. (NYSE:RHD), up 28.5% to $8.20 after the Yellow Pages publisher reported first-quarter revenue of $674.7 million versus $661.3 million during the same time a year ago. Wall Street analysts anticipated $664.5 million in revenue.

• Central Garden & Pet Co. (Nasdaq:CENT), up 28.4% to $5.38 after the Walnut Creek, Calif.-based supplier of pet supplies and lawn products reported better-than-expected revenue for the second quarter.

• Gibraltar Industries, Inc. (Nasdaq:ROCK), up 27.8% to $14.12 after the Buffalo-based maker of building products posted first-quarter earnings of $6.7 million, or $0.22 per share, topping Wall Street’s expectation of earning $0.14 per share. A year earlier, Gibraltar posted earnings of $6.2 million, or $0.21 per share.

Biggest percentage losers:

• Kingsway Financial Services Inc. (NYSE:KFS), down 30.6% to $9.83 after the insurance holding company reported a first-quarter loss of $34.4 million, or $0.62 per share, versus analysts’ expectation of earning $0.38 per share. A year earlier, the Canada-based firm posted a profit of $19.6 million, or $0.35 per share.

• Akeena Solar, Inc. (Nasdaq:AKNS), down 19.4% to $5.35 after the Los Gatos, Calif.-based firm reported a first-quarter loss of $4.6 million, or $0.16 per share, which missed Wall Street’s expectation of losing $0.13 per share. During the year-ago quarter, the designer and installer of solar panel systems posted a loss of $0.9 million, or $0.06 per share.

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