* 2012 Net profit halved to 221.1 mln euros
* Proposes dividend of 1.75 euros per share for 2012
* Says ready to invest 2 billion euros over next four years (Adds background, details)
PARIS, March 28 (Reuters) - French investment company Wendel's net profit halved in 2012 as it wrote down the value of a stake in building materials maker Saint-Gobain .
Wendel, which also has holdings in testing and inspection firm Bureau Veritas and electrical equipment maker Legrand, posted net profit of 221.1 million euros ($282 million) on Thursday, down from 525.4 million euros in 2011.
Profit in 2011 had been boosted by a sale of Legrand shares.
It booked a 414-million-euro writedown in the value of Saint-Gobain shares after that company's cashflow prospects were reined in because of a weak European construction industry, Wendel said in a statement.
Net asset value (NAV), Wendel's most closely watched indicator, stood at 6.56 billion euros, or 132.5 euros per share, as of March 18 compared with 106.7 euros per share in late November and 98.6 euros a year ago.
NAV indicates how much its investments are worth and is calculated by subtracting liabilities from assets.
Its highest published NAV per share since 2005 was 135 euros in November 2007 and the lowest was 31 euros in May 2009, according to data available on Wendel's website.
Wendel, which also has stakes in construction chemicals company Materis and leather finishing products specialist Stahl, said it was ready to invest 2 billion euros in the next four years, or about 500 million euros per year, in emerging markets as well as Europe and North America.
Full-year sales rose 12.6 percent to 6.7 billion euros, compared with a Thomson Reuters I/B/E/S average forecast of 6.6 billion euros. They stood at 5.9 billion in 2011 and 5 billion in 2010.
Wendel said it would offer shareholders a dividend of 1.75 euros for 2012, up from 1.30 euros paid in 2011.
Shares in Wendel, which have risen 5 percent since the start of the year, were trading up 0.3 percent at 0850 GMT.
($1 = 0.7824 euros) (Reporting by Alice Cannet; Editing by Elena Berton; Editing by Tom Pfeiffer)