The Government has said it will take action "very soon" to stop investors from bulk-buying property.
Fine Gael Minister of State Martin Heydon said planning and taxation were among the ways being explored to tackle the issue.
But he said it accounts for less than 1% of the market and was not a widespread issue.
He said they were consulting with the Attorney General to ensure that any decisions do not have a knock-on impact on people trying to buy homes.
He also said supporting Sinn Féin proposals on the issue would be a "massive disservice to first-time buyers" because the Irish economy was not big enough to supply the estimated 35,000 houses a year needed and the Government does not want to take action that would stop some of that supply.
Sinn Féin TD Imelda Munster said her party would propose measures next week which would end special tax deals for these funds, apply stamp duty surcharges to them and introduce a legislative cap on what investors can buy.
She said it was madness what is happening across the State, and that is a direct consequence of Government policy.
Social Democrats co-leader Catherine Murphy said she believed the number of properties being bought by investor funds was closer to 20%.
And she said the narrative needed to change that building homes was not the role of Government and there need to be a more interventionist approach.