Invesco PowerShares, the IL-based fourth-largest US issuer of exchange-traded funds, recently launched a laddered-strategy bond fund that aims to preserve capital and generate consistent income in an uncertain interest-rate environment. The newly-launched PowerShares Ladderite 0-5 Year Corporate Bond Portfolio (LDRI) invests in corporate bonds with 5 years or less remaining to their maturity and qualifies as a strategic-beta fixed income …