Week in Tech : Bolt, Facebook Messenger and Snapchat

LOS ANGELES -- The top tech news for the week was highlighted by a new Instagram app, larger than expected Twitter popularity, an unexpected takeover bid for no. 4 wireless carrier T-Mobile and big changes at Facebook's mobile app.

-- Bolt. This new app is Instagram's answer to Snapchat, home of the messages that disappear within up to 10 seconds. Bolt won't actually be released here in the United States until later in the year, but it sounds really novel.

Instagram says Bolt will be the fastest way to share photos with one friend.You open the app, snap a shot, and out it goes. The hitch -- it can't be saved, just like Snapchat. Unlike other photo apps, the pictures won't get saved to your phone. Instagram launched the app in New Zealand, Singapore and S. Africa. Look for it here soon.

Snapchat, on the other hand, may have new investors that will bring its valuation to a whopping $10 billion. The company is talking with Chinese giant Alibaba, according to Bloomberg, on a new round of investment. Snapchat is wildly popular, used by young people to send over 700 million photos daily.

-- That other social network, Twitter, has been under pressure from Wall Street to show growth, and this week it did, announcing a larger than expected user base of 271 million folks using the service. The company says that's a 24% increase from a year ago.

-- T-Mobile, the scrappy no. 4 wireless carrier, saw shares of its stock soar after French telecom company Iliad offered to acquire the firm. No. 3 wireless carrier Sprint is also thought to be interested in snapping up T-Mobile, which said it now has 50 million customers.

-- Facebook hinted at this change in April, but this week it became effective. Folks who use the Facebook app to chat with their friends on mobile phones now have to download a second app, Facebook Messenger, if they want to keep talking. Facebook said it made the change to have Messenger be a stronger, more robust app, but some fans aren't happy about having two apps open at the same time.

Finally, the top app download chart is highlighted by -- you guessed it, Facebook Messenger at Apple iTunes, no. 2 on Android ---how else were Facebook's 1 billion plus user base going to see their messages?

Follow Jefferson Graham on Twitter.