NY -- Standard&Poor's CreditWire 9/1/98 -- Standard&Poor's today affirmed its ratings on Boeing Co. and related entities (see list below), following the firm's announcement that it will repurchase up to 15 percent of its outstanding shares of common stock (worth about $4.5 billion at the current share price) over time, in line with the goal to enhance shareholder value. The outlook remains negative. While stock buybacks represent a shift in the company's historically conservative financial policy, they are expected to be funded primarily from internally generated cash flow and excess cash balances. Furthermore, share repurchases are anticipated to be paced over the next several years to maintain financial flexibility. Ratings on Boeing are supported by the