We set up a multiperiod, CAPM-type model with imperfect competition between investors in case of an additional price-insensitive market participant. The motivation for this additional actor comes from the ECB’s announcement to buy a substantial amount of securities “whatever it takes” which reflects the willingness to trade in a entirely price-inelastic way. Our model explains the effects on demand functions, equilibrium prices, portfolio holdings and investors’ expected utility. The interaction of price-inelastic additional demand by the ECB, on the one hand, and imperfect competition, on the other hand, causes differentiated results regarding timing strategies, development of prices over time, and utility implications.

我们建立了一个多周期的 CAPM 型模型，在存在额外的对价格不敏感的市场参与者的情况下，投资者之间存在不完全竞争。这一额外参与者的动机来自欧洲央行宣布“不惜一切代价”购买大量证券，这反映了以完全价格无弹性的方式进行交易的意愿。我们的模型解释了对需求函数、均衡价格、投资组合持有量和投资者预期效用的影响。一方面，欧洲央行的价格无弹性的额外需求与不完全竞争之间的相互作用，导致了时机策略、价格随时间的变化和效用影响方面的差异化结果。