BlackBerry Ltd's (BBRY) shares took a hit on Wednesday after International Business Machines Corp (IBM) said it planned to partner with Apple Inc (APPL) to sell iPhones and iPads loaded with applications geared to business users.

The Apple-IBM tie up, beginning this fall, is set to target the customer base that BlackBerry is attempting to woo as part of a turnaround under new Chief Executive Officer John Chen.

"It is not a crushing blow at this early stage, but ‎it is a negative for BlackBerry," said IDC analyst John Jackson. "There can be little question that it is unwelcome, if not entirely unexpected news."

BlackBerry's stock has been on a tear this year. As of Tuesday, it was up more than 50 percent as some investors have become more optimistic about the company's future.

But news of the Apple-IBM tie-up took some of the steam out of the stock on Wednesday.

Shares in BlackBerry fell 4.7 percent to $10.77 on Nasdaq and 4.3 percent to C$11.62 on the Toronto Stock Exchange after analysts said the alliance could hurt BlackBerry's turnaround plans.

IBM said late Tuesday that it planned to release more than 100 apps targeting industry-specific issues in retail, healthcare, banking, travel, transportation and telecommunications.

The companies will also offer services geared toward security and mobile device management, an area viewed as BlackBerry's strong suit and a key selling point for the company in its battle to win back market share from Apple's iPhone and a slew of devices powered by Google Inc's (GOOG) Android software.

"The partnership's software around data security and device

management pose immediate threats to mobile device management (MDM) software solutions deployed by firms such as BlackBerry and MobileIron (MOBL)," said Morningstar analyst Brian Colello in a note to clients.

"Even if Apple-IBM's security 'mousetrap' isn't as good as ones offered by BlackBerry and others, these MDM vendors will

have to overcome the extremely high hurdle of displacing IBM's mobile device software preloaded on iPhones and iPads," he said.

BlackBerry, however, down played the threat posed by the IBM-Apple alliance.

"The news that Apple is partnering with IBM to expand into the enterprise mobility market only underscores the ongoing need for secure end-to-end enterprise mobility solutions like those BlackBerry has delivered for years," said the company in a brief statement.

BlackBerry said it remained the leader in this market with the necessary software and network to secure data for enterprise clients.