Jefferies, a US mid-market investment bank, has bought Helix Associates, a London-based private equity placement agency, to strengthen links with its lucrative private equity client base.

Helix's recent mandates include the £400m (€581m) first time fund for Exponent Private Equity, a spin-out from 3i, as well as the €650m ($821m) inaugural fund for Altor, a Nordic mid-market firm. It is currently advising Bridgepoint on its third fund, which is expected to close at €2.5bn within the next month.