It’s a tale of two social media stocks: Twitter has jumped 2 percent over the past week, while Facebook is down by almost 3 percent. That echoes the trend thus far in 2015, with the microblogging site rising 34 percent while the social network is only up 4.

And the Twitter surge has Jonathan Krinsky, chief market technician at MKM Partners, predicting further upside for the stock.

He says that Twitter shares are now breaking above their long downtrend, and that the key $50 resistance level has now become support.

“We think it probably heads up to the next resistance at $56, and that gives you a pretty nice upside,” he said.

“Ultimately, we think it’s not out of the question to see it retest those old highs, up around $70, if we are looking down the next 18 months,” Krinsky added.

But the fundamentals say quite the opposite, according to David Seaburg, head of equity sales trading at Cowen and Co.

“I can’t stand Twitter,” he said. “I look at Twitter’s valuation—totally extended. … They are great at monetizing, no doubt, but they are capped in terms of user growth, and that’s what’s going to get the multiple premium that a growth investor is going to be willing to pay. So Twitter, I’m a seller here.”

On the other hand, Seaburg is into Facebook.

“They’ve got multiple levers that they can pull, which is why people want to be invested in this space,” he said. “It’s really about the future monetization.”

Seaburg says Facebook shares will rise to $91, if not $100—nicely above Wednesday’s closing price of $81.67