Shake Shack big earnings report continues to power shares, now up 21 percent this month

Shake Shack, in addition to its Chicago Dogs and double cheeseburgers, is cooking up super-sized stock gains this month after a surprisingly strong quarter.

Shares of the New York company have been on a roll since becoming a public company earlier this year. They have more than tripling since its initial public offering price of $21 in January.

After rising another 5 percent Friday, shares are up 21 percent this month, and 70 percent over the past three months.

Wall Street investors have been buying shares of fast casual chains that are posed to grow. Shake Shack, for example, has 66 stores, but it plans to open 10 more in the country this year and at least five internationally. Other companies, such as rival burger chain The Habit Restaurants Inc. and Mediterranean-style restaurant chain Zoe's Kitchen Inc., have taken off since their IPOs.

On Wednesday, Shake Shack topped Wall Street Wall Street expectations for the first quarter earnings and its revenue spiked 56 percent.

Shares of Shake Shack Inc. rose $3.89 to $69.39 Friday.