If you describe something as a bellwether, you mean that it is an indication of the way a situation is changing.
[mainly US, journalism]
For decades the company was the bellwether of the British economy.
IBM is considered the bellwether stock on Wall Street.
bellwether in British English
(ˈbɛlˌwɛðə)
noun
1.
a sheep that leads the herd, often bearing a bell
2.
a leader, esp one followed unquestioningly
bellwether in American English
(ˈbɛlˌwɛðər)
noun
1.
a male sheep, usually wearing a bell, that leads the flock
2.
a leader, esp. of a sheeplike crowd
3.
anything suggesting the general tendency or direction of events, style, etc.
Word origin
ME: see bell1 & wether
Examples of 'bellwether' in a sentence
bellwether
Next, a favourite bellwether of the high street, underlined the challenges this week when it posted weak results.
Times, Sunday Times (2016)
This distributes a dizzying range of electronic products and is a bellwether of world economic recovery.
Times, Sunday Times (2010)
Nor has her quixotic campaign in a bellwether seat yet ignited.
Times, Sunday Times (2010)
It's not been your more bellwether economic stocks.
Times, Sunday Times (2015)
It's a bellwether stock and always under scrutiny.
Times, Sunday Times (2010)
The high street bellwether could also face hostile questions from shareholders at its annual meeting on Tuesday.
Times, Sunday Times (2015)
Steel is a good bellwether of economic activity as it is used in construction, cars and manufacturing.
Times, Sunday Times (2010)
Often seen as a bellwether for economic activity, haulage companies need less congestion and better traffic management systems.
Times, Sunday Times (2010)
The advertising sector is a bellwether for economic confidence given that it is a gauge of how much the world's companies are spending.
Times, Sunday Times (2014)
She leaves vacant her Ohio seat, a bellwether and one of the most vulnerable.
Times, Sunday Times (2007)
Punters backed the multinational recruitment company and bellwether of the global economy to have done well in America in particular, where the recovery continues.