After a record-breaking start to the year, the FTSE 100 is actually down for 2017

LONDON - Britain's benchmark share index, the FTSE 100, slipped into negative territory for the year on Monday, meaning it now stands below where it ended 2016.

The FTSE 100 went on an unmatched run at the end of 2016 and beginning of 2017, closing higher on 14 consecutive trading days and celebrating 12 all-time closing highs in a row.

That record-breaking run was driven by the FTSE's inverse relationship with the pound: when sterling is weak, the FTSE is strong, and vice versa.

About 70% of the revenue earned by FTSE 100 companies is derived abroad, meaning they make more money when sterling is weak, and less when it is strong. That is because the index is full of mining companies, oil firms, and pharmaceutical giants that use the UK as a base but tend to denominate their assets in dollars. Exporters also prefer a weak pound: It makes their goods cheaper than international competitors. That relationship is explained by JP Morgan Asset Management here.

Sterling has rallied in recent weeks thanks to a combination of a weak dollar, driven by market uncertainty surrounding President Trump's policies, and optimism surrounding UK Prime Minister Theresa May's Brexit policy.

The FTSE hit a low of 7,130 points on Monday morning, around 12 points lower than its opening level on 2017's first trading day, January 3. As of 10.10 a.m. GMT (5.10 a.m. ET) the index has pulled a little higher, and is trading at 7,153 points, a fall of 0.64% on the day.

Here's how the Footsie looks: