Increasing by is the antonym of decreasing by. When a value is increasing, it means that it is getting larger over time. Conversely, when a value is decreasing, it is getting smaller. The term 'decreasing by' indicates a decline in something's value or quantity by a significant amount. However, when we use the term 'increasing by,' we imply that something has grown in value or quantity by a certain amount. For example, if a stock price decreases by 10%, it means it has fallen down by the said percentage. On the contrary, if a stock price increases by 10%, it means it has grown up by the stated percentage.