Previous research suggests that a policy interest rate cut below the reversal interest rate reverses the intended effect of monetary policy and becomes contractionary for lending. This paper is an empirical investigation into whether the reversal interest rate was breached in the Swedish negative interest rate environment between February 2015 and July 2016. We find that banks with a greater reliance on deposit funding were adversely affected by the negative interest rate environment, relative to other banks. This is because deposit rates are constrained by a zero lower bound, since banks are reluctant to introduce negative deposit rates for fear of deposit withdrawals. We show with a difference-in-differences approach that the most affected banks reduced loans to households and raised 5 year mortgage lending rates, as compared to the less affected banks, in the negative interest rate environment. These banks also experienced a drop in profitability, suggesting that the zero lower bound on deposits caused the lending spread of banks to be squeezed. However, we do not find evidence that the reversal rate has been breached. / Tidigare forskning menar att en sänkning av styrräntan under brytpunktsräntan gör att penningpolitiken får motsatt effekt och blir åtstramande för utlåning. Denna rapport är en empirisk studie av huruvida brytpunktsräntan passerades i det negativa ränteläget mellan februari 2015 och juli 2016 i Sverige. Våra resultat pekar på att banker vars finansiering till större del bestod av inlåning påverkades negativt av den negativa styrräntan, relativt till andra banker. Detta beror på att inlåningsräntor är begränsade av en lägre nedre gräns på noll procent. Banker är ovilliga att introducera negativa inlåningsräntor för att undvika att kunder tar ut sina insättningar och håller kontanter istället. Vi visar med en "difference-in-differences"-analys att de mest påverkade bankerna minskade lån till hushåll och höjde bolåneräntor med 5-åriga löptider, relativt till mindre påverkade banker, som konsekvens av den negativa styrräntan. Dessa banker upplevde även en minskning av lönsamhet, vilket indikerar att noll som en nedre gräns på inlåningsräntor bidrog till att bankernas räntemarginaler minskade. Vi hittar dock inga bevis på att brytpunktsräntan har passerats.

The introduction of negative interest rates, as an additional tool of unconventional monetary policy in recent years, leads to many, yet largely polarized debates about the implications of the unconventional monetary policy of central banks. The main reason for their introduction in some economies, namely the threat of deflation, is also questioned, as well as the negative side effects of this instrument on financial stability and economic growth, and finally, their limited scope is under scrutiny. Due to the still insufficient research in this field, the aim of the diploma thesis is to evaluate the concerns and the main long-term risks and impacts of the monetary policy using negative interest rates in the context of deflation threats. The analysis of available data confirms both the concerns about the negative effects of negative interest rates on the banking sector, the recovery process of public finances, the possible rise of a price bubble on the financial markets and real estate markets, or on the possibility of excessive risk taking, and on the other hand draws attention to the direct dependence between negative impacts and the duration of monetary policy using negative interest rates.