English to French Bus/Financial Finance (general) prêts

"A.’s capital adequacy has somewhat weakened during the last few years. While Tier 1 and total capital ratios were still acceptable at year-end 2007, in 2008 Tier 1 declined to X,X%. To reinforce solvency, ** the parent has subscribed Tier 2 subordinated debt **, bringing up total capital adequacy to X,X% at year-end 2008. "

"la maison mère a souscrit de nouveaux emprunts subordonnés portant sur (??) des fonds propres complémentaires" ?
Cet agencement de termes me semble plutôt bancal. Qu'en pensez-vous ? Un grand merci par avance pour vos conseils.