Usually, when one insider buys stock, it might not be a monumental event. But when multiple insiders are buying like they did in the case of First Financial Corporation (NASDAQ:THFF), that sends out a positive message to the company's shareholders.

While insider transactions are not the most important thing when it comes to long-term investing, we would consider it foolish to ignore insider transactions altogether.

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Over the last year, we can see that the biggest insider purchase was by Independent Director William Brighton for US$98k worth of shares, at about US$48.99 per share. We do like to see buying, but this purchase was made at well below the current price of US$55.46. Because the shares were purchased at a lower price, this particular buy doesn't tell us much about how insiders feel about the current share price.

In the last twelve months insiders purchased 6.55k shares for US$325k. But they sold 1.10k shares for US$57k. In the last twelve months there was more buying than selling by First Financial insiders. The chart below shows insider transactions (by companies and individuals) over the last year. By clicking on the graph below, you can see the precise details of each insider transaction!

View our latest analysis for First Financial

First Financial is not the only stock insiders are buying. So take a peek at this free list of under-the-radar companies with insider buying.

We've only seen a tiny insider purchase valued at US$1.7k, in the last three months. Looking at the net result, we don't think these recent trades shed much light on how insiders, as a group, are feeling about the company's prospects.

For a common shareholder, it is worth checking how many shares are held by company insiders. I reckon it's a good sign if insiders own a significant number of shares in the company. Insiders own 5.0% of First Financial shares, worth about US$33m. While this is a strong but not outstanding level of insider ownership, it's enough to indicate some alignment between management and smaller shareholders.

Insider purchases may have been minimal, in the last three months, but there was no selling at all. That said, the purchases were not large. On a brighter note, the transactions over the last year are encouraging. Insiders own shares in First Financial and we see no evidence to suggest they are worried about the future. While it's good to be aware of what's going on with the insider's ownership and transactions, we make sure to also consider what risks are facing a stock before making any investment decision. Case in point: We've spotted 1 warning sign for First Financial you should be aware of.