Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: H&R Block (NYSE: HRB) shares are down 11.5% in trading today, with more than three times the volume of an average day.

So what: H&R Block announced it may not offer tax refund loans during the upcoming 2011 tax season because of a disagreement with HSBC (NYSE: HBC), which underwrites refund loans for the company. The Internal Revenue Service will no longer provide lenders a digital indicator that helps them know whether consumers qualify for the refund they have filed for, and as a result, HSBC no longer wants to provide the loans.

Now what: H&R Block has sued HSBC. H&R Block has a contract with the bank to supply refund loans through 2013, and doesn't view the IRS' decision to withdraw its digital indicator as a reason for HSBC to stop providing the loans. Historically, tax preparation services such as H&R Block and Jackson Hewitt (NYSE: JTX) have promoted refund loans as a way for consumers to get instant cash when they file their returns. Cash-strapped consumers may opt for an alternate tax filing services if H&R Block isn't able to resolve the dispute with HSBC.

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Fool contributor April Taylor does not own shares of the companies mentioned. Try any of our Foolish newsletter services free for 30 days. True to its name, The Motley Fool is made up of a motley assortment of writers and analysts, each with a unique perspective; sometimes we agree, sometimes we disagree, but we all believe in the power of learning from each other through our Foolish community. The Motley Fool has a disclosure policy.