Meet the Swedish sisters who became billionaires this week

The two daughters of Swedish industrialist Fredrik Lundberg have become billionaires this week as shares of the family's investment company climbed to a record high.

Louise Lindh (36) and Katarina Martinson (35) each own a 14 per cent economic interest in publicly traded Lundbergfoeretagen, according to the company's 2015 annual report.

Shares of the Stockholm-based business have risen 28 per cent in the past 12 months and matched their all-time high of 517.5 Swedish kronor ($61.08) on Thursday.

The stock is in part benefiting from a rise in real estate values in Stockholm, where apartment prices have climbed 24 per cent in the past year, according to researcher Real Capital Analytics.

Property made up about 40 per cent of the company’s 59 billion kronor of market-valued assets at the end of May.

A scarcity of publicly available shares - the family controls 70 per cent of the capital and more than 90 per cent of the voting stock - is amplifying the price gains, according to Gustav Oesterberg, a Stockholm-based analyst at Pareto Securities.

The siblings’ ownership increased from 7.6 per cent at the start of 2015 after their father almost doubled their stakes in the family business by transferring some of his holdings.

The value of those shares, along with dividends and interests in other publicly traded assets, has given each of the sisters a $1.1 billion fortune, according to the Bloomberg Billionaires Index.

The family declined to comment on their wealth, according to spokesman Roger Ekstrom. About four-fifths of the company's net asset value comes from listed stocks, including property business Hufvudstaden, which manages commercial and residential properties mainly in Stockholm, and Holmen, which owns forest land it uses to produce paper products.

Unlisted real estate arm Fastighets Lundberg makes up the remainder. Lundbergs was founded by the sisters' grandfather, Lars Erik Lundberg, an engineer who in 1944 started his own construction firm focused on developing residential buildings.

- Bloomberg