Shares in Ireland's largest company, building materials giant CRH, as well as its biggest hotel group, Dalata, have been shorted by investors as the Covid-19 pandemic sees the world's economies hammered.
When investors short a share, they are betting the price will drop.
They borrow the company's shares from other shareholders and can profit if the price falls by buying back shares at a lower cost, to return them to their original owner.
But short positions can turn sour if the share price in the target company rises.
US global investment firm Bridgewater Associates, which before the Covid-19 pandemic had about $160bn (€148bn) of assets under management, has taken a 0.54pc short position in CRH. It has notified the position to the Central Bank of Ireland.
But short positions can turn sour if the share price in the target company rises, as Dalata's (+21pc) did yesterday.
Bridgewater's short position is currently equivalent to about €80m of CRH stock, based on its market capitalisation yesterday of almost €14.9bn. CRH's shares have declined by about a third in the past month.
JP Morgan Asset Management has taken a 0.61pc short position in Dalata. That represents about €3m of the hotel group's shares, based on its €502m market capitalisation yesterday.
US international hedge fund and quantitative investment management firm WorldQuant has notified the Central Bank that it has a 0.52pc short position in Dalata - the equivalent of €2.6m of the company's shares.
Dalata's shares have fallen by about 44pc in the past month.
WorldQuant had assets under management of about $25bn before the crisis unfolded. It was founded by CEO Igor Tulchinsky in 2007.
Bridgewater Associates is headed by co-chief executives David McCormick and Eileen Murray.
Mr McCormick is a former US Treasury under-secretary for international affairs, having served under the George W Bush administration during the last global financial crisis. Before that, he held senior roles with the National Security Council and the US Department of Commerce.
Ms Murray previously worked with Morgan Stanley and Credit Suisse. She is a member of the Irish Arts Center in New York. Her father's ancestors emigrated from Cork to the US during the famine.
CRH, whose chief executive is Albert Manifold, has operations across the United States, Europe and elsewhere.
Last week, Swedish activist investor Cevian Capital raised its stake in CRH to above 3pc for the first time. The Swedish company first revealed over a year ago that it had taken a stake in CRH.
Cevian Capital partner Gustav Lundgren said last week that the firm remained a long-term investor in CRH and was lifting its stake in the Irish company "at a share price that is well below our view of the value of the group's assets". He said Cevian remained "convinced" of CRH's potential.
Dalata, whose CEO is Pat McCann, said yesterday that it is cancelling its final dividend and has the resources to see it through the crisis. It said it has cash resources totalling €80m and can avail of additional undrawn committed debt facilities of about €65m.