To estimate the cost of debt for Apple using the yield on its most recently issued $30-$year bond Or their longest maturity bond, youll need to search for Apples bond information on one of the sites you mentioned. Heres how you can proceed for each website:$1.$ Business Insider BondsGo to the Business Insider Bonds page.Use the search function on the site to enter Apple or Apple Inc.Look for the most recent bond issue with the longest maturity $($preferably $30$ years$).$ Note the details including the yield, which represents the cost of debt$\mathrm{.}2.$ FINRA Market DataVisit FINRAs Market Data site.Utilize the search tool to look up Apple Inc. in the corporate and agency bonds section.Find Apples longest maturity bond and observe the yield. This is particularly useful as FINRA provides comprehensive data including yield to maturity which is a good proxy for cost of debt$\mathrm{.}3.$ MorningstarIf you have access to Morningstar, navigate to the bond section after logging in$.$Search for Apple and check for bond listings.Locate the bond with the longest duration and note its yield.What to Look for:When you access these sites, youre looking to find the most recent bond issued by Apple with the longest maturity. The bonds yield at issuance will give you the cost of debt. This yield is what investors demand to lend to Apple and thus, what Apple would likely pay for new debt issued under similar conditions.Example of What You Might Find:For instance, if you found an Apple $30-$year bond with a yield of $3\mathrm{.}0\%,$ that would be an estimate of Apples current cost of debt. This figure helps in various financial models and investment analyses to assess Apples debt servicing costs relative to its profits and cash flow. You can use morningstar as well.