What: June was a really volatile month for Halcon Resources Corp (NYSE:HK) investors. The stock was up as much as 25% no less than three times during the month, only to end up just more than 10% by the time the month ended. Fueling that double-digit rise was news of strong insider buying by the CEO, as well as a credit-rating upgrade from a major ratings agency.

So what: On the first day of the month, the company disclosed that CEO Floyd Wilson bought 1 million shares on the open market the week prior. While the purchase only cost him slightly more than $1 million, it did boost his total stock holding to 4.75 million shares, so it significantly increased his direct ownership. A large insider purchase like that typically suggests that the insiders are bullish, and see a higher stock price in the company's future.

The other news that drove the stock during the month was an announcement that S&P upgraded the company's corporate credit rating to B- from SD, or selective default. It made the move after deciding that additional debt-for-equity swaps, which the rating agency tends to view as a distressed exchange, are unlikely to occur again. That said, despite the upgrade, S&P still maintains a negative outlook on the company, as its leverage could continue to deteriorate to unsustainable levels.

Now what: June's strong showing aside, Halcon Resources still has a long road ahead of it. The company has a mountain of debt, and therefore it needs meaningfully higher oil prices in order to maintain that leverage. Until either oil prices surge much higher, or the company addresses its debt situation, it's best for investors to watch this stock from the sidelines for now, as the risk remains that it could one day go bankrupt.