You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
European_Central_Bank

Context:
The ECB's first supplementary longer-term refinancing operation (LTRO) with a six-month maturity was announced March 2008. Previously the longest tender offered was three months. It announced two 3-month and one 6-month full allotment of Long Term Refinancing Operations (LTROs). The first tender was settled 3 April, and was more than four times oversubscribed. The €25 billion auction drew bids amounting to €103.1 billion, from 177 banks. Another six-month tender was allotted on 9 July, again to the amount of €25 billion. The first 12-month LTRO in June 2009 had close to 1100 bidders.

Question:
What is an LTRO?

longer-term refinancing operation