MAAS Group Holdings' (ASX:MGH) decision to sell its construction materials unit to Heidelberg Materials Australia for up to AU$1.7 billion in cash was wholly unexpected, according to a Monday report by Jefferies.

Jefferies believes that the company's decision to exit its core business and re-focus on next-gen infrastructure could be a "great thing".

For now, however, it has shaken the confidence of shareholders who had viewed the unit as the main reason to invest in the business, Jefferies said.

The firm sees the stock's 30% drop in the last three days as excessive and noted that the funds received from the sale will be used to reduce the company's debt.

Jefferies has a buy rating for the company and an AU$5.25 price target.

Shares of the company fell 3% in recent Tuesday trade.