BlackRock has boosted its position in Seacor Marine Holdings amid a weeks-long fall in the Houston-based diversified marine services company's shares.

The New York investment manager on 31 December bought 131,480 shares of the owner at $13.97 each for $1.81m, according to a Securities and Exchange Commission filing.

The New York-listed stock has fallen to $9.38 through Thursday's mid-afternoon trading since then, lowering the latest investment's value by 32% to $1.23m.