The Dow Jones Industrial Average (^DJI 0.17%) was up more than 128 points as of 11:30 a.m. EDT Tuesday. A few tech stocks were experiencing significant rallies, including Twitter (TWTR), BlackBerry (BB -1.09%), and Yahoo! (NASDAQ: YHOO).

Twitter adds new CFO
Shares of social media giant Twitter rose more than 4% by late morning after the company announced that it had hired Anthony Noto as its new CFO. Mike Gupta will give up the CFO office to become Twitter's senior vice president of strategic investments. Noto was previously a managing director in Goldman Sachs' technology, media, and telecom investment banking group.

Investors are evidently pleased with the hire -- and perhaps for good reason. Although Twitter had a strong performance in the weeks that followed its IPO last fall, recent months have not been the greatest for shareholders: The stock is down more than 37% year to date, though it has rebounded somewhat lately. A new CFO won't immediately reverse Twitter's problems, which have largely centered around user growth (or lack thereof), but a shift in management could result in some positive changes down the line.

BlackBerry rallies on Passport hopes
Shares of struggling Canadian handset giant BlackBerry gained nearly 2%. BlackBerry shares are up almost 40% in the last month. To some extent, that extended rally may have been the byproduct of short covering: BlackBerry, which has largely been left for dead, has a short interest of roughly 30%. To stem potential losses, BlackBerry shorts may be buying shares in the open market, leading to outsized gains.

But there's also more fundamental hope for BlackBerry. The company's next handset, the BB10-powered Passport, has actually generated some positive buzz. The Passport is an odd-looking phone with a wide body and rectangular design, but it offers users a large screen and physical keyboard. Although the Passport is unlikely to put up sales numbers anywhere near the next iPhone or Galaxy device, it could help BlackBerry stem its ongoing losses. CEO John Chen has said his company intends to be operating near breakeven by the end of the year. 

Yahoo! saves a doomed show
Yahoo! shares rose nearly 1% after the company announced that it would host the sixth season of the television show Community. The series appeared dead after cancellation by NBC, where it had aired for the past five years. Despite a strong cult following, Community may not have been popular enough to sustain its run on network TV. 

But Community will continue -- fans will just have to turn to Yahoo! Screen to see the show. For investors, the company's decision to pick up Community signals a shift in Yahoo!'s business -- past reports indicated that Yahoo! had a strong desire to enter the Internet video business; adopting Community is perhaps the first step forward for a more video-focused Yahoo!.

Editor's note: A previous version of this article referred to the BlackBerry Passport device as the Passbook. The Motley Fool regrets the error.