Why am I getting list elements < 0 ?

[Mark17]

Hi all!

Here's some code:

price_chg = np.arange(-10,11,2)

stock_prices = [100]

for i in range(10001):
    if (stock_prices[-1] + np.random.choice(price_chg)) < 0:
        stock_prices.append(0)
        continue
    else:
        stock_prices.append(stock_prices[-1] + np.random.choice(price_chg))

Why is the if block failing to keep negative integers out of the list?