Allstate Corp. may lose its spot as the second top auto insurer in the nation if Chevy Chase, Md.-based GEICO’s total written premiums continue to swell.

According to SNL Financial, GEICO wrote $4.4 billion in personal auto premiums in 2012’s third quarter while Northbrook, Ill.-based Allstate wrote $4.47 billion, a difference of about $79 million.

While GEICO’s premiums have grown an average of 7.1% during the past five years, Allstate’s have decreased by 1.9%.

The online insurance marketer Esurance, acquired by Allstate in 2011, has seen growth. However, it only accounts for 5.7% of Allstate’s total premium volume.

Warren Buffet

Berkshire Hathaway, headed by one of the country’s top investors Warren Buffett, owns GEICO.

State Farm is the nation’s largest auto insurer by premium volume. According to A.M. Best, GEICO’s Berkshire Hathaway reported $15.3 billion in premium in 2011; Allstate posted $17.4 billion and State Farm wrote $30 billion in premiums for the year. Fourth and fifth on the A.M. Best premium list for 2011 were Progressive (4th) with $13.4 billion, and Farmers with nearly $9.8 billion.

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