The nation's largest private auto insurer, State Farm Mutual Automobile Insurance Co., received approvals for several significant rate hikes on its personal auto business during the month of April that could potentially increase its premiums by $325.2 million.

California's regulator signed off on what may be the most impactful rate change approved in April, according to an analysis by S&P Global Market Intelligence. State Farm received a 6.9% rate increase in the Golden State that could see its premiums increase by $231.7 million. Nevada and Tennessee are two other states where the insurer received rate hike approvals during the month.

Safeco Insurance Co. of America, a Liberty Mutual Holding Co. Inc. subsidiary, also received a 6.9% rate increase on its private-passenger auto business in California, which could bump its premiums up by $26.0 million. In total, Liberty Mutual could see its premiums increase by $44.1 million from approvals received in April.

Regulators in 10 states approved Nationwide Mutual Group's rate-hike applications which could potentially see its premiums increase by $81.3 million. Rate filings in South Carolina and Georgia accounted approximately 85% of the premiums increase. Rate changes in South Carolina, however, will not go into effect until March 30 of next year on its renewal business.

This analysis included 467 rate filings, of which 324 were for increases and only 18 were for rate decreases. The remaining rate filings had no rate impact.

Click here for a template providing rate changes for a selected entity, state or type of insurance over a selected time period using interpretive charts and histograms. With this template, one can also view information on each filing along with key metrics related to premiums, approval time and affected policyholders. Click here for a webinar on how to use the above template and to understand the calculation methodology used in it.