MELVILLE, N.Y. ( TheStreet) -- Fonar Corp. ( FONR) shares tumbled Monday on above-average volume after the medical equipment maker reported a third-quarter loss that swelled from a year earlier. Fonar reported a fiscal first-quarter net loss of $1.74 million, or 35 cents a share, widening from the year-ago loss of $450,000, or 9 cents a share. Revenue climbed 10% from the year-ago period to $7.49 million. According to Thomson Reuters, there are no analyst targets for the company. Last month, Fonar reported full-year 2009 earnings of 21 cents a share, swinging from a year-ago loss of $2.76 a share, which helped shares rally sharply higher. Lately, though, shares of Fonar were falling by 50 cents, or 21.1%, to $1.89. More than 284,000 shares changed hands by 3:30 p.m. EST Monday, compared to the stock's 50-day average daily volume of 125,000, according to the Nasdaq. Fonar has a 5.2 million-share float with a short ratio of only 0.3% as of Oct. 30, according to Yahoo! Finance. Insiders hold 2.5% of the company's shares, with another 7.2% owned by institutions. -- Written by Robert Holmes in New York. Check out all of Monday's high-volume, under-$5 stocks at the Dollar Store Follow Robert Holmes on Twitter and become a fan of TheStreet.com on Facebook.