The announcement of the convertible senior notes offering by Rocket Lab is likely to have a negative short-term impact on the stock price due to potential dilution of existing shares. Investors often view convertible debt offerings as a sign that the company may be in need of cash, which can be interpreted as a negative signal about the company's current financial health or future prospects. Additionally, the conversion of debt to equity can dilute the value of existing shares, leading to a decrease in stock price.