By Helen Reid
LONDON (Reuters) - Anxiety over emerging market assets sent Britain's FTSE 100 tumbling on Friday as a currency crisis in Turkey deepened and Russia's rouble extended losses, dragging exposed stocks down.
The FTSE 100 (FTSE) fell 0.7 percent by 0830 GMT but was still on track to end the week in the black with a 0.5 percent rise, its best performance in a month. It outperformed Europe's STOXX 600 and Germany's DAX, which was down 1.6 percent.
Many UK-listed companies derive a significant chunk of revenues from emerging markets, and several Russian companies are listed on the British stock market.
Russian gold miner Evraz (L:EVRE) was the worst-performing FTSE 100 stock, down 6.6 percent after broker VTB Capital downgraded it and the rouble fell to its lowest since July 2016 on anxiety over a fresh round of U.S. sanctions.
Russia-exposed miners Polymetal (L:POLYP) and Kaz Minerals (L:KAZ) fell 2.2 and 1.7 percent.
A slide in the Turkish lira to record lows, after President Tayyip Erdogan dismissed investors' concerns, sent tremors across other emerging markets, with South Africa's rand falling to a six-week low.
This weighed on South Africa-exposed bank Investec (L:INVP), whose shares fell 2.4 percent. Emerging markets-focused lender Standard Chartered (L:STAN) fell 1 percent.
UK mid-caps with exposure to Turkey and nearby emerging markets were also bruised.
Travel operator On The Beach (L:OTB) fell 3.2 percent, while TBC Bank (L:TBCG), a Georgian lender, declined 3.5 percent.
"Whilst generally EM economies are much stronger than they were 20 or 30 years ago you've still got some countries that are a bit of a mess," said Peter Elston, chief investment officer at Seneca Investment Managers.
"That's occasionally going to cause problems for the asset class as a whole, as it is doing at the moment."
The FTSE 100 fell despite a slide in sterling, which usually supports the exporter-heavy index. The negative relationship between the two has evaporated recently. https://reut.rs/2OkPhOi
Miners were the biggest weight on the FTSE 100, with Fresnillo (L:FRES), Randgold Resources (L:RRS), Anglo American (L:AAL), Antofagasta (L:ANTO), Glencore (L:GLEN), and Rio Tinto (L:RIO) all down between 1.6 and 3.2 percent as copper prices fell on a stronger dollar.
Outside of EM-driven moves, shares in engine maker Rolls-Royce (L:RR) fell 3.1 percent after JP Morgan downgraded the stock to "underweight".
"Relative to other civil aerospace stocks we follow, we think Rolls-Royce now offers investors a less attractive risk-reward," JPM analysts wrote, arguing the firm is showing deteriorating earnings quality.
The FTSE 250 (FTMC) fell less sharply, down 0.4 percent thanks to its less internationally exposed constituents.
"Mid-caps fell horribly following the (Brexit) vote, and they've since made back everything they've lost and more, which suggests they have been able to thrive in this post-ref vote environment," said Seneca's Elston.
However, he added, "earnings have been very mixed."
Analysts have been cautious on mid-cap earnings, while the index has been declining since a record high hit on June 14.
(This version of the story has been refiled to fix embedded graphic)