股票涨停买是指投资者在股票价格涨停时买入股票的行为。股票涨停是由于市场对该股票的买入需求超过了卖出供应，导致股票价格暂时无法继续上涨。投资者选择在股票涨停时买入股票的原因可能有以下几点：

1. 短期赚取利润：股票涨停意味着市场对该股票的买入需求旺盛，投资者可能通过短期交易赚取利润。

2. 股票潜力：投资者认为该股票有较大的上涨空间，即使涨停了也有可能继续上涨。

3. 超跌反弹：如果一只股票在之前的时间里一直跌幅较大，当股票出现涨停时，投资者可能认为是超跌反弹的机会。

4. 市场情绪：市场情绪对股票价格有较大影响，当市场情绪乐观时，投资者可能会选择在涨停时买入股票。

然而，投资者在股票涨停时买入股票也存在风险，因为股票价格涨停后可能会出现回调，投资者需要谨慎评估风险并做出理性的决策。Investing in stocks that have hit the limit up price is a practice where investors purchase stocks when their prices have reached the highest daily limit allowed by the exchange. This usually happens when there is an influx of buying interest that surpasses the selling supply, causing the stock price to temporarily halt its upward movement.

There are several reasons why investors may choose to buy stocks that have hit the limit up price:

1. Short-term profit: Investors may see an opportunity to make quick profits by trading stocks that have hit the limit up price.

2. Growth potential: Investors believe that the stock has the potential for further growth even after hitting the limit up price.

3. Oversold bounce: If a stock has been experiencing significant declines in the past, hitting the limit up price may be a sign of an oversold bounce.

4. Market sentiment: Market sentiment can heavily influence stock prices, and investors may choose to buy stocks that have hit the limit up price during optimistic market conditions.

However, there are risks involved in buying stocks that have hit the limit up price, as stock prices may experience a pullback after hitting the limit up. Investors should carefully assess the risks and make informed decisions when engaging in this practice.