Sprint’s stock fell 4% yesterday as investors reacted to a report that the risk of the carrier going bankrupt was increasing. Bernstein analyst Craig Moffett downgraded Sprint shares from “market-perform” to “underperform” based on the news.

While the company, which happens to be the third largest wireless provider in the US, has had a long string of poor quarters over the past few years, analysts had high hopes for the carrier after it finally became an iPhone partner late last fall…

But then earlier this month, Sprint was once again left out of Apple’s keynote as the company announced two new LTE-flavored iPads for Verizon and AT&T. Both carriers have since announced record-breaking tablet sales.

Moffett believes that Sprint could be in even more trouble if Apple releases an LTE handset later this year. The carrier, which was actually the first to claim “4G” data speeds here in the states, has a nationwide WiMax network, but is looking to make the switch to the more common LTE technology sometime in the near future.

And that switch can’t come soon enough. Between the costs of upgrading its network and the $15 billion dollar debt it’s paying out as part of its iPhone agreement, Sprint can’t afford to be left out of another major Apple release.

What do you think will happen to Sprint?

[Reuters]