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: Shares of lottery and gambling service provider Scientific Games (Nasdaq: SGMS) have hit the jackpot today, up by 14% at the high, after the U.S. Department of Justice adopted a new stance toward online gaming.

So what: The new opinion frees states to facilitate various forms of online gaming. The DoJ had previously interpreted the 1961 Wire Act as prohibiting online bets, but it has now changed its tune and now believes the language of the law only applies to sports betting.

Now what: States can now implement online gambling other than sports betting within their borders, and could open new markets to companies like Scientific Games and International Game Technology (NYSE: IGT), who is also seeing gains today. Legalizing and regulating online gaming could bring in billions in tax revenue while providing a safer environment for players. The opinion comes after a massive crackdown on online poker sites like Full Tilt Poker and Absolute Poker, both of which are based outside of the U.S., earlier this year.

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Fool contributor Evan Niu holds no position in any company mentioned. Click here to see his holdings and a short bio. The Motley Fool owns shares of International Game Technology. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.