Boston is in the midst of a high-rise condo development boom, and everyone wants a piece of the action. Buildings such as Millennium Tower and Twenty Two Liberty are selling completely off-market, prior to opening, at staggering rates. Boston’s high-end housing market is so hot these days even brand new condos that haven’t been lived in yet are being flipped for big profits.

That’s what happened at Twenty Two Liberty, a new glass-walled condo building on Fan Pier with views of the Boston harbor and the downtown skyline. Six of the 118 units were sold by their original buyers before the building even opened at the start of this year — each one for at least $500,000 above the original price. Five more units are currently listed for sale. 22 Liberty hit the market just as demand for the upper end of the luxury market was surging, and there was little competition. Millennium Tower Boston is already 95% pre-sold out in less than 18 months, including the penthouse, which is currently under agreement, and the tower is still six months from final completion.

The median price for condos in nine downtown neighborhoods, South Boston, and Charlestown jumped nearly 10 percent from 2014 levels, to $680,000. Prices for luxury condos — buildings with concierge service and parking — climbed at double that rate, to a median of $1.75 million. That translates into nearly $1,200 per square foot. And four in 10 condos sold above asking price.

Developers are gradually shifting to meet that market, planning more condos after a several-year run of building apartments all over town. In the first nine months of 2015, according to city figures, 28 percent of new housing permitted in Boston was for-sale condos, up from 26 percent in 2014 and 17 percent in 2013. In the three months ending Sept. 31, more than 40 percent of permitted units were condos.

Are you looking to Buy a Boston Condo? Create an account today to get access to thousands of listings!