What it means
In everyday speech positive feedback means praise, but in systems thinking it means a loop that magnifies a change. A small rise leads to a bigger rise, and a small fall leads to a bigger fall.
The opposite is negative feedback, where a change sets off forces that pull things back towards balance. Markets provide many examples.
When a share price rises, newspapers and social media notice, more investors buy to avoid missing out, and the extra buying pushes the price higher. Bubbles grow this way, and so do crashes when the loop runs in reverse.
Credit markets show the same pattern. Rising property prices raise the value of collateral, banks lend more against it, buyers borrow more and prices rise again.
When prices turn down, collateral values fall, lenders pull back and forced sales push prices lower. Positive feedback also exists inside businesses.
A company with a strong brand attracts more customers, which gives it more data and cash to improve its product, which attracts still more customers. These network and scale effects can produce winner-takes-most markets, which is why investors pay close attention to them.
For managers and analysts the practical lesson is to recognise loops early and plan for them. Spotting one lets you ask what would break it, such as a tightening of credit, a regulation or a limit on capacity, and how fast the loop could reverse.
Risk limits, stress tests and trading circuit breakers are all designed to interrupt dangerous loops. Spotting a positive feedback loop is not the same as timing it.
Loops can run far longer than seems reasonable, and many investors who correctly called a bubble lost money by betting against it too early. The practical approach is to size positions so that you can survive the loop continuing and to define in advance what evidence would tell you it has turned.
In practice
Real-world examples.
Example
A technology share rises 10% after strong results, and fund managers who track momentum buy more of it. The new buying lifts the price a further 8% over the next fortnight, which attracts still more buyers. A sceptical analyst points out that nothing about the company itself has changed in those two weeks.
Example
A property developer sees prices in a district climbing and borrows to buy more land. Lenders, impressed by the rising values of existing sites, offer larger loans, and the extra building activity pushes up prices further.
Example
A subscription app grows its user base, which lets it spend more on product improvements. Better features win more users, and a larger user base makes the app more valuable to advertisers. The extra advertising income then pays for yet more development, so the loop strengthens the company's position without any outside help.
Case study
Seen in the real world.
Copperline Metals is a fictional mining company whose share price started rising after a new discovery. Analysts upgraded their forecasts, index funds increased their holdings and the share price roughly doubled in four months.
The company used its higher share price to raise fresh capital cheaply and buy a neighbouring mine, which made the story look even better. In this illustrative case, the loop reversed when metal prices dipped, as investors who had bought for momentum sold together, and the board later admitted that it had treated the price rise as proof of value instead of questioning how much of it was the loop itself.
After the episode the audit committee asked management to separate two ideas in its reports: the value of the company's reserves, and the market's reaction to news about them. A short note on what share of the price rise could be explained by changes in forecast cash flow, and what share looked like momentum, became part of the quarterly pack. It did not stop the cycle, but it kept the board from mistaking the share price for a scorecard.
Watch out
Common mistakes.
- Assuming positive feedback means something good, when it simply means a loop that reinforces whatever direction it started in.
- Treating a price that keeps rising as evidence that the company is worth that price.
- Forgetting that the loop works in reverse, so the same mechanism that inflates a bubble also deepens a crash.
Questions
People also ask.
How is positive feedback different from negative feedback?
Negative feedback pushes a system back towards balance, such as a price falling because high prices attract sellers, while positive feedback pushes it further away.
Can positive feedback be useful in business?
Yes, because network effects and economies of scale are positive loops that can build a lasting advantage when managed well.
How do regulators deal with dangerous loops?
They use tools such as trading halts, capital buffers, margin requirements and stress tests to slow down or break the cycle.
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