NEW YORK (TheStreet) -- First Acceptance Corp. (FAC), Berkshire Hathaway (BRK.A) and Ambac (ABK) have had their short ratios drop dramatically. Though that might indicate investors are less bearish on those insurance stocks, it's not that simple.First Acceptance's short ratio on Tuesday dropped from 35.1 to 21.2, covering nearly 14 days of shorted stock sales in a day. The stock price fell 0.9%. Warren Buffett's Berkshire, hardly the darling of short sellers, saw its short position decline from 5.9 to 2.6. The stock decreased 0.2%. Ambac's dropped from 9.9 to 7.2, and its stock price rose 6%. The average insurer has a short ratio of 5.8, an increase of 0.3 days in the past month. The short ratio is an indication of how many days that sales of a stock have been sold by investors betting on price declines. If those investors, sometimes called "shorts," cover their positions in sufficient numbers as a stock rises, share prices can be propelled further. Insurers' stock prices have hit a wall after soaring from the depths of the stock-market low reached a year ago. President Barack Obama is proposing sweeping changes to U.S. health care, while some other politicians are opposed to rising insurance rates, creating undertainty among investors. Still, First Acceptance benefitted from a ratings upgrade on Tuesday. Berkshire is an active stock, trading at more than three times normal levels in the past month. And Ambac is a speculative stock, trading at less than $1. Investors are bracing themselves for Ambac's 2009 financial results. Insurers appear vulnerable, according to short ratios. Primus Guaranty ( PRS) has a whopping 30.7 short ratio. Triple-S Management ( GTS) has a short ratio of 25.1, and Markel ( MKL) has a short ratio of 24.2. Each of those stocks has seen rising short interest but also higher share prices. Primus is up 23% in the past month, while Triple-S has risen 8%, and Markel has advanced 7%. Citizens ( CIA) has a short ratio of 20.1, a decline from last month. Its price has risen 16%. -- Reported by Gavin Magor in Jupiter, Fla.