Are screen superheroes losing their power?

If you're a Hollywood superhero, only one thing hurts worse than an energy ray or a kryptonite bullet, and that's a thumbs-down from Wall Street.

"The Death of Superheroes" is the title of a strongly worded report released last week by research firm Susquehanna Financial Group. The message: Anyone wearing tights is in trouble.

Analyst Vasily Karasyov spells out what moviegoers may already suspect: The studios have used up their best caped crusaders and are now digging through the leftovers. There have been 16 superhero movies released since 2000, by Karasyov's count, and only four major franchises: X-Men (with a worldwide box-office gross of $1.8 billion), Batman ($1.3 billion), Spider-Man ($2.5 billion) and newcomer Iron Man ($1.2 billion). "The chances of finding a breakout property are diminishing fast," Karasyov writes, adding, "We think superhero films are getting riskier with each new one making the transition to the screen."

But there's a stealth franchise happening. "Thor," "The Incredible Hulk" and "Captain America: The First Avenger" could be called prequels to Joss Whedon's "The Avengers," which will round them all up -- plus Iron Man -- in May. Adding up the worldwide grosses of those heroes (excluding the just-released Captain, and leaning heavily on Iron Man), this quasi-franchise is already hovering around $2 billion.

Are superheroes "headed for extinction," as Karasyov claims? Or are their flags still flying high? The opening-weekend revenues of "Captain America," which should be announced Sunday, might offer a clue.