A bull market is one in which the general trend is up. A bull market could refer to the fate of one particular asset such as gold or copper, a sector, such as technology or commodities or the whole stock market in general.
The rise in house prices in the UK over the 2010s could be referred to as a bull market. The fact the rise is ongoing creates the phenomenon and can be seen as furthering price rises as more people want to invest in stock they see as going up, now and in the future. This fuels a bull market, as might other demands – for example the rise in Asia’s middle classes could start a bull market in gold as more people have wealth with which to buy gold, increasing demand and pushing up the price. An ongoing price rise could be referred to as a ‘bull-run’.
Ongoing bull markets, such as the one seen across the stock market over the last decade see a lot of optimism but can also lead to investor caution as they see a limit to price growth approaching. The longer a bull market goes on, the more likely it is to end. This also plays into the theory of market rotations: that the stock market is due a correction every ten years or so.
Once an investor believes a bull market has run its course they might look to buy a safer asset such as gold, which will typically hold value and very often increase in value as other areas of the market fall.
The opposite of a bull market is a bear market.