Last month, Wall Street was hit with the news of Detroit becoming the largest U.S. city to file for bankruptcy. While the once booming hub of American manufacturing had tried to make negotiations with creditors, the city's dire financial state made its bankruptcy filing ultimately inevitable. Since Detroit's bankruptcy filing, municipal bond investors have understandably become quite wary about this relatively safe asset class.

Despite this incident, however, analysts have emphasized that not every city, county, or state is on its way to becoming the "next" Detroit. That said, investors should always keep a close eye on any news concerning their respective municipal investments, as well as the latest ratings reports. Here, we highlight Moody's recent upgrades and downgrades seen over the past two weeks:

Upgrades

• East Norriton-Plymouth-Whitpain Joint Sewer Authority, PA: Moody's upgraded this sewer authority's $23 million revenue bonds, series 2013, to Aa3. The Aa3 rating reflects the credit strength of the member townships of East Norriton, Plymouth and Whitpain (GO rated Aaa) given their ability to use any available funds of the township to make payments to the authority. The rating also incorporates the satisfactory legal covenants, minimal capital needs of the treatment plant and strong liquidity levels.
• Successor Agency to the City of Santa Barbara Redevelopment Agency, CA: Moody's has upgraded this agency's Series 2001A, Series 2003A, and Series 2004A Tax Allocation Bonds (TABs) from Ba1 to Baa3. The rating agency noted the following strengths: strong second payment debt service coverage, stable assessed value, and no pass-through obligations.
• City of Dover Water and Sewer Enterprise, DE: Moody's upgraded this city's $6.22 million Water and Sewer Revenue Bonds, Series 2013 to Aa3. The upgrade to Aa3 reflects strong debt service coverage resulting from a sequence of rate increases over the past few years, a moderate debt burden, and a solid financial and operational management characterized by multi-year planning and a series of strong policies.
• Illinois Housing Development Authority: Moody's upgraded this state's Multi-Family Housing Revenue Bonds, 2001 Series A1 from Baa3 to Baa1, based on the improved financial position due to the $4,745,000 partial bond redemption on May 31, 2013.

Downgrades

• Perry Public Schools, MI: Moody's downgraded the general obligation rating of Perry Public Schools in Michigan to Ba1 from Baa2. The Ba1 rating reflects a multi-year trend of operating shortfalls that has resulted in a deficit General Fund balance position. The trend of operational imbalance is largely attributable to the district's delayed enactment of expenditure reductions to offset revenue declines associated with declining enrollment, driven by outmigration of students to neighboring districts and demographic factors.
• Gooding County School District No. 232 (Wendell), Idaho: Moody's has downgraded this school district's general obligation bonds to Baa1 from A3. The downgrade reflects the steady degradation of the district's finances over the last several years, leading to reserve and liquidity levels that are well below the median for similarly rated districts. The rating also incorporates the small tax base with concentration in the dairy industry, below-average socioeconomic measures reflective of the agricultural economy, and somewhat high debt burden.
• Holt Public School's, MI: Moody's has downgraded this school's general obligation rating to A1 from Aa3. Concurrently, a negative outlook has been assigned. The downgrade reflects the school's elevated debt burden, limited revenue raising flexibility, the trend of General Fund operating deficits and declining reserves, and the debt structure that exposes the district to renewal risk for a direct placement loan, interest rate risk with the variable rate loan as well as basis risk from associated swaps.
• Town of Winchester, CT: Moody's downgraded this town's general obligation rating to A3 from A2 and assigned a negative outlook. The downgrade reflects Moody's belief that Winchester's already narrow financial position likely experienced further deterioration in fiscal 2012 and will remain pressured over the near term.
• Town of Templeton, MA: Moody's has lowered this town's general obligation rating to A2 from A1 and assigned a negative outlook. The downgrade reflects the town's deteriorating financial position, which is driven by rising expenditures and annual transfers to the sewer fund to pay for ongoing projects.
• City of Brentwood, MO: Moody's has downgraded this city's outstanding certificates of participation to A1 from Aa3. The downgrade reflects the city's weakened financial position due to financial challenges over the last 3-5 years despite a recent operating surplus.
• City of Manchester, NH: Moody's has downgraded this city's long-term general obligation rating to Aa2 from Aa1. The outlook has been revised to stable from negative. Concurrently, Moody's has downgraded the city's appropriation-backed school facility revenue bonds to Aa3.
• McKeesport Area School District, PA: Moody's lowered its rating on this school district's general obligation bonds to A3 from A2. Concurrently, Moody's assigns an A3 rating the district's $26.6 million General Obligation Bonds, Series of 2013 and confirms the A1 enhanced rating. The outlook is negative.
• State of Alaska Airports System: Moody's downgraded this airport's revenue bonds to A1 from Aa3. The downgrade is based on the change in the airport system's market position due primarily to the slowdown in global air cargo trends.
• City of Minneapolis, MN: Moody's has downgraded this city's outstanding general obligation bonds to Aa1 from Aaa. Moody's has also removed the rating from review for possible downgrade and the outlook has been revised to stable.
• Pinckney Community Schools, MI: Moody's has downgraded the underlying general obligation rating to Baa3 from Baa1. The downgrade reflects significant structural imbalance of the district's general operations, which is expected to have resulted in a deficit General Fund balance at the close of fiscal 2013.